JPS6046150B2 - X-ray fluorescent film - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to
It relates to a phosphor film such as the input surface of a linear fluorochrome multiplier tube.

[Technical background of the invention and its problems] The intensifying screen will be described in detail as the main application of the present invention.

The intensifying screen 1 is used with a film 3 interposed therebetween as shown in FIG. 7, and emits light due to X-ray stimulation, which sensitizes the film. A portion of the incident X-rays is absorbed by an intensifying screen 1 located at the front of the film, and further absorbed by an intensifying screen 2 located at the rear of the film. The intensifier papers 1 and 2 emit light due to X-ray absorption, and the film 3 is exposed to light by the emitted light.
Conventionally, in order to improve the image quality of film, studies have been made on the type of phosphor applied to intensifying paper, the structure of intensifying screen, etc. Regarding phosphors, one has been developed that has a large amount of X-ray absorption and high luminous efficiency, and the conventionally used one is CaWO. In addition, 12OBr/Tb) (Y,, Gd). O. S/Tb
) La. O. S/Tb, Gd, O, S/', etc. have been studied and put into practical use. Regarding the intensifying paper structure, for example, it is possible to reduce the quantum noise of X-rays by using multiple phosphor layers and reducing the luminous efficiency of the layer near the film, or by using a colored intensifying paper mount. By absorbing the light emitted by the phosphor, the scattering of light reflected by the mount is eliminated and the contrast of the image is improved.

[Object of the invention] The present invention is different from the conventional ones and is based on a new idea.
A portion of the light emitted by the phosphor is absorbed by the phosphor's own body color to reduce light scattering and improve image contrast and resolution. This is an attempt to reduce quantum noise.

[Summary of the invention] This invention is Y.

O2S/TO) (YNGd). O3S/Tb)Gd2
O2S/To) Ll2O2S/T0 and LU2O2
This is an X-ray fluorescent film formed by depositing on a substrate at least one type of phosphor selected from S/Tb and having an absorption band in the blue to green spectral region. FIG. 1 illustrates the present invention. As an example of a fluorescent film having an absorption band in the blue to green spectral region, a body-colored phosphor 11 is coated in one layer on a substrate 12 made of wallpaper. It is an intensifying screen. Considering the component A perpendicular to the intensifying paper surface and the component B tilted 0 from the perpendicular direction to the light emitted from the phosphor particles 11a in the figure, it is clear that the optical path until reaching the film 13 surface is B. It will be longer. By the way, the rate of decrease of light in the middle of the optical path increases in the colored phosphor layer, and therefore the difference in intensity between the A and B lights on the film surface is much greater than in the conventional case without body color. becomes larger. The difference becomes larger as the inclination O of the light from the vertical direction increases, and as a result, the scattering of light within the plane of the intensifying paper is greatly reduced, and the contrast and resolution of the image are improved. FIG. 2 shows a two-layer intensifying screen, where the same reference numerals as in FIG. 1 indicate the same parts.

Here, the C layer of the fluorescent film 14 is a colored phosphor layer, and the D layer is a non-colored phosphor layer. The effect is that the body color of the C layer reduces light scattering and improves contrast, and the C layer near the film surface absorbs X-rays because of its body color, the emission intensity is lower than that of the D layer, which is farther from the film surface. The light and shade of light emission caused by variations in light emission is reduced on the film surface, and as a result, quantum noise is reduced. Figure 3 is 3
A fluorescent film 15 having a three-layer structure is coated on a substrate 12 using a layer-coating intensifying screen.

The E and G layers are colored phosphor layers, and the F layer is a phosphor layer with no body color or a very weak body color. The E layer is weakly colored, and the G layer is strongly colored. The effect is that the strong G layer weakens the reflected light from the mount, improving the contrast, and as in the case of FIG. 2, the effect of the ElF layer reduces quantum noise. An example of a phosphor having an absorption band in the blue to green spectral region is n-activated L.
An example is n2O2s. Here Ln is Y. ．． Gd.
．． It is at least one type of LllLulYb.
These oxysulfide phosphors can be colored by means such as ball milling or pressing. For example, Y
2O2S/11), Gd2O2S/Tb, . La2O2
When S/TO is subjected to balling treatment, Y2O2S becomes about 434nTrL and Gd2O
2S is about 469r1m and Ll2O2S is about 533nrr
1. A colored phosphor having an absorption peak is obtained. The intensity of the body color becomes stronger as the ball milling time increases, so it can be controlled by the ball milling time. The light emitted from these phosphors has a line spectrum distribution depending on Tb, and the light emitting region can be set as shown in the following table, for example. In this way, a Tb-activated oxysulfide phosphor can be used to create a phosphor that absorbs a portion of the emitted light depending on its body color.

[Embodiments of the invention] Specific examples will be described below.

Example 1 Y activated with Tb, . Oxysulfide solid solution of Gd (YG
d) Add body color to 202S/Tb.

First, by mixing 1 part phosphor, 2 parts glass beads, and 1 part pure water and ball milling for 1 hour, a colored phosphor with a reflection spectrum shown in Figure 5 is obtained, and the X-ray excitation brightness is It decreases by about 15%. This phosphor was uniformly coated to a thickness of about 100μ, and the same sensitivity as that of the conventional (YGd) 202S/Tb
As shown in Figure 6, the resolution and contrast were greatly improved when compared with the intensifying screen.

Example 2 Instead of (YGd)202S/TO in Example 1, L22O2S/'[1), Cd2O2S/Tb. L.U.
2O2S/Tb, (YNGd,.Yb)202S/Tb
The same effect of improving resolution and contrast was obtained by adding body color using a ball mill.

Example 3 As shown in FIG. 2, the phosphor layer is divided into two layers, and the C layer is CUO. The D layer is colored (Y..Gd)20 with CawO4 phosphor containing 1%.

The S/Tb phosphors are each coated to a thickness of 50μ. C. ．．
D Due to the colored phosphors in both layers, the resolution contrast was very good. Also, the emission intensity of the C layer is about 70% of that of the D layer.
The quantum noise was reduced by about 20% compared to conventional products.

Although the above embodiments 1 to 3 have been described with respect to the intensifying paper, similar effects can be obtained by using a similar fluorescent film on the input fluorescent surface of an X-ray fluorescent plate or an X-ray fluorescent multiplier.

As a phosphor for an X-ray phosphor plate, Gd2O2S/Tb or La2O2S/Tb, whose emission color matches the visibility, is effective.

[Brief explanation of the drawing]

1 to 3 are schematic cross-sectional views of an X-ray intensifying screen explaining an embodiment of the present invention, FIGS. 4 to 6 are reflection spectrum distribution charts of a phosphor, and FIG. 7 is a diagram of a conventional X-ray intensifying screen. FIG. 2 is a schematic cross-sectional view of a line intensifying screen. 11...fluorescent body, 12...substrate, 13...
···film.

Claims (1)

[Claims] 1 Y_2O_2S/Tb, (Y, Gd)_2O_2S
/Tb, Gd_2O_2S/Tb, La_2O_2S/
An X-ray fluorescent film comprising at least one phosphor selected from Tb and Lu_2O_2S/Tb, which has an absorption band in the blue to green spectral region, coated on a substrate.