JPH02280100A - Manufacturing method of luminescent screen for roentgen diagnosis, sensitization or memory sheet - Google Patents

Abstract

PURPOSE: To provide a various sheet of high resolution by configuring a member with a honeycomb micro structure which contains walls and spaces, and filling spaces of the microstructure with light emitting materials. CONSTITUTION: A female-type gap 12 which allows free communication is filled with a molding material. In that case, the entire metal mold can be coated with a plastic by a thickness of about 20μm at its surface. A plastic micro structure, thus configured, is separated from a metal mold. While allowing precipitation of nickel on a substrate by electric plating, a metal micro structure is molded in a temporary mold of a molding material through a precipitation by electric plating on the substrate. The micro structure contains honeycomb-like spaces 22 separated each other by partitions 23. After the metal micro structure is removed from the substrate, the honeycomb body 22 is filled with a light emitting material 17, and then, the both sides of structure is covered with a thin translucent polyimide sheet 19 which is used as a protective film.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a method for producing luminescent screens, sensitizers or memory sheets for X-ray diagnosis.

Prior art When converting X-ray radiation into visible light, in a luminescent screen or in an intensifying sheet, the amount of light transmitted increases with increasing thickness of the layer of luminescent material and decreases due to light scattering in the luminescent material. between the increasing local resolution and
A compromise needs to be reached. Therefore, when using a sensitizing sort that is attached to both sides of an X-ray film with front- or back-sheets, a certain type of sensitizing sheet is used, which is divided into different sensitivity grades depending on the specialty of medical diagnosis. exists. Sheets of the highest sensitivity class, ie those with a high sensitizing effect, require only a small X-ray dose, but such sheets have a significantly poorer resolution. On the other hand, thin-line notebooks, which are characterized by a particularly good resolution, are memory sheets that are read out by means of a narrowly focused laser beam, which requires significantly higher radiation requirements in diagnostic radiography technology. When using , scattering of the light to be read out in the luminescent material generally has no role. This is because light can be transferred from a sufficiently thick light guide to the photomultiplier. However, the resolution decreases with the increase in the thickness of the layer of memory luminescent material due to the scattering of the laser beam, which is a measure of the resolution, so that a situation similar to that in the case of luminescent screens or intensifying sheets arises. The following several proposals have been made as a solution. That is, the luminescent substance is used as a column (Kre
stel, BildgebendeSysteme f
uer die medizinische Diag
to nost+; Siemens AG (1980)
, p. 235) or as separate straftures separated from each other (European Patent Application No. 0175578A2
(No. 1), on a support, in which case the spatial distribution of the luminescent material is such that the spread of the scattered light is prevented or at least reduced.

It has often been proposed to eliminate the drawback of low resolution when the thickness of the layer of luminescent material is large in the following manner. That is, the luminescent material is housed in a honeycomb-like mesh with dimensions as small as possible, the light-transparent or light-reflective walls of this mesh preventing the lateral spread of the light or laser beam, i.e. the resolution (European Patent Application Publication No. 0126)
564A2).

In order to make full use of the incident X-ray rays, the thickness h of the layer of luminescent material is tried to be 500-1000 μm, and in order to further avoid image disturbances, the thickness of the wall distributing the luminescent material It is generally assumed that the depth should not exceed 10 μm. Starting from this assumption, the desired aspect ratio of the wall h/x is 5
Values on the order of 00-1000 are obtained. In this case, the extremely thin walls are oriented as parallel to the incident X-ray beam as possible. These requirements are not met at all, or at least not simultaneously, with the prior known solution proposals and at a reasonable cost. For this reason, luminescent substances housed in honeycomb-like networks are rarely implemented in practice.

Problem to be Solved by the Invention It is an object of the present invention to provide a method for producing luminescent screens, intensifying or memory sheets for X-ray diagnosis, which simultaneously fulfills the above-mentioned requirements.

Means for Solving the Problem In order to solve this problem, the configuration shown in the characterizing part of claim 1 has been proposed. The associated dependent claims point out advantageous embodiments of this solution. In this case, the method according to the invention not only satisfies the requirements set hitherto for the compartmentalization of luminescent substances, but also ensures that the microstructures provided for the compartmentalization of luminescent substances are significantly smaller. Become. Improvements in X-ray diagnostics are therefore expected not only in areas where conventional sensitizing sheets are already used, but also in areas where sensitizing sheets produced by the method of the present invention are not used due to high demands on resolution or on the back side. Even in areas where only single-sided sheets could be used, they can now be used.

In the area of dental radiography, where particularly high demands on resolution are usually operated without the use of brightening sheets,
Set. Patients are therefore exposed to significantly higher radiation doses during dental X-ray diagnosis. With the method according to the invention, a diameter of less than 30 μm and a wall thickness of approximately 5 μm is obtained.
The sensitizing sheet produced in this way makes it possible to accommodate the luminescent material in cells with micrometer partition walls, which allows for the number of pairs of approximately 14 lines per mm required in this area of use. resolution can be obtained. The use of this new intensifying sheet reduces the required X-ray dose by a factor of about 10, given the same resolution.

Similarly high resolution is required in mammography, for example when the smallest calcium deposits are to be diagnosed.

Therefore, conventionally, in this area of use, only a back sheet for drawing fine lines is used without a front sheet. In this case, by using the sensitizing sheet of the present invention as the front and back sheets, the required radiation dose can be reduced to about one-third if the resolution is the same.

The manufacturing method according to the invention provides a luminescent screen, sensitizer or memory sheet in which the partition walls constituting the honeycomb-shaped, luminescent substance-filled chambers are formed from plastic (in case a) or from metal (in case b). is manufactured. a
In case b) (microstructure with partitions made of plastic) fewer manufacturing steps are required than in case b (microstructure with partitions made of metal). This partition wall is therefore manufactured from metal only when: That is, only when this is required for X-ray beams due to good mechanical stability, longer service life or higher robustness.
Constructed of metal.

DESCRIPTION OF EMBODIMENTS Next, both embodiments described above will be explained with reference to the drawings. 1st
Fig. 5 shows the individual steps of the manufacturing method of microstructures made of plastic (case a), and factor 6
Figures 1 to 11 show the steps in the case of metal microstructures.

In both cases of FIG. 1 or FIG. 6, the material is made of polymethylmethacrylic resin (PMMA) with a thickness of 0.3 mm.
A disk 1 of mm is used. This is metal disk 2
It is fixedly attached to the top. This PMM
The A-disk is irradiated by a substantially perfectly parallel synchrotron beam 4 through an X-ray mask 3, as shown in FIG. 1 or FIG. 6. This X-ray mask slightly weakens the X-ray beam. It is composed of a support 5 that absorbs the X-ray beam and an absorber 6a or 6b that strongly absorbs the X-ray beam. In the areas 7 or 8 not blocked by this absorber, the PMMA is chemically changed in the beam and further removed in the developer. As a result, only the PMMA partitions 9 (in case a, FIG. 2) or only the PMMA pillars 10 (in case b, FIG. 7) remain on the substrate 2. By depositing nickel by electroplating on a metal substrate 2 used as an electrode, a female metal mold (in case a, Fig. 3) or a male metal mold (in case b, Fig. 8) is produced. Ru. The metal shell mold (Figure 3) is a Ninkel column 1 with a height of 300 μm.
Consists of 1. These nickel columns are separated from each other by partition walls 12 that are connected to each other in a mesh pattern.
In this case, the width of these gaps has a value of 5 μm. two/
Ker column II has a diameter of 30 μm.

The male metal mold (FIG. 8) has a partition 13 having a width of 5 μm and a height of 300 μm. On the other hand, the mutually isolated cavities 14 have a diameter of 30 μm.

The freely communicating gap 12 of the female mold (FIG. 3) is filled with molding material. In this case, the entire metal mold can be covered with plastic to a thickness of about 20 μm on the surface. An integrated cover 18 with connected partitions 15 (FIGS. 4 and 5) is thus formed. The plastic microstructure configured in this way is then separated from the metal mold. Depending on the dimensions of the metal mold, the honeycomb-like cavities of the microstructure are
The partition wall 15 has a diameter of 0 μm and a wall thickness of 5 μm. A light-reflecting cover is provided on the partition wall 15, and a roughly honeycomb-shaped cavity 16 is filled with a luminescent material 17. The plastic microstructure filled with the luminescent substance 17 is then covered with a polyimide sheet 19 with a thickness of approximately 10 μm, which is used as a protective film.
(Figure 5).

In the case of the male type (figure $8), the honeycomb body is filled with molding material. As a result, after separation of the metal from the mold, a temporary mold (FIG. 9) of molding material is formed having columns 20. The molding materials are separated from each other by gaps 21 which are interconnected in a network. In this case, the molding of the metal male mold (FIG. 8) with the molding material is carried out as follows. That is, a temporary mold (FIG. 9) consisting of a molding material is glued onto a substrate (not shown) on which nickel can be deposited by electroplating. By electroplating deposition on this substrate,
A metal microstructure (FIG. 1O) is produced from a preliminary mold of molding material (FIG. 9), which has honeycomb-shaped cavities 22 separated from one another by partition walls 23. In this case, the dimensions of the honeycomb body and the partition walls correspond to the dimensions of the male mold made of metal according to FIG. After removing the metal microstructure (FIG. 10) from the substrate, the structure 22 is filled with a luminescent material 17, and the strut is covered on both sides with a thin transparent polyimide sheet 19, which serves as a protective layer. .

The individualized luminescent material produced in this way can be used as a luminescent screen, a front or back sensitizing sheet, and as a memory channel.

In the case of microstructures made of plastic (FIGS. 4 and 5), when used as a back-sensitizing sheet or as a memory card, it is also possible to make the cover considerably thicker.

In addition, in the case of a microstructure made of metal (Figs. 10 and 11), the metal partition wall 23 is left fixedly on the substrate, and this struf- ture is attached only on one side.
It can also be covered with a polyimide sheet 19 used as a protective layer.

By using a substantially parallel synchrotron beam 4, vertically positioned microstructures are formed at all locations on the substrate 2. Therefore, all partition walls 15 or 23 of the honeycomb-like microstructure are completely parallel.

As shown in FIG. 12, a point-shaped X-ray source 24 is used for X-ray diagnosis. The X-ray beam 25 is therefore emitted like light from a point 26. If a honeycomb-shaped microstructure manufactured by a synchrotron beam and having parallel walls 23 is used to house the luminescent substance 17 in a single chamber, the X-ray beam 25 and the partition walls 23 will not be parallel everywhere. First, the absorption of the X-ray beam in the partition wall 23 depends on the location. At the edges of the luminescent screen, intensifier or memory sheet, the X-ray beam is therefore not very effectively converted into visible light.

This is indicated by the length of arrow 27. The edge areas therefore appear more or less dark, for example on a luminescent screen, or more or less bright on a negative film attached to the back side of the intensifying sheet.

If a completely uniform conversion of the X-ray beam into visible light is required in the case of X-ray diagnosis,
- As shown in FIG. 13 - The irradiation of the PMMA disc I through the X-ray mask 3 can be carried out by the beam of a high-power X-ray tube 28 and not by a Lee synchrotron beam. In this case, a high-energy beam 29 for changing the material properties of PMMA is emitted from the point 26a, so that the shadow of the X-ray mask 3 forms a microstructure. In the case of this microstructure, the walls are formed not to be parallel but to be focused towards this point 26a. For this irradiation, the spacing 30 between the high-power X-ray tube 28 and the PMMA disk I is selected to be: That is, it is selected to be exactly equal to the distance between the microstructure filled with luminescent material 17 and the X-ray source 24 in the case of X-ray diagnosis. After a similar sequence of processing as shown in FIGS. 7 to 11, microstructures (FIG. 14) are formed. The metal wall 31 of this microstructure is designed in such a way that it can be focused precisely onto the focusing point 26 of the X-ray source 24 used in X-ray diagnosis.

Similar microstructures (not shown) with plastic walls focused to point 26 are shown in FIGS.
It is formed by the processing sequence shown in FIG. Therefore, the X-ray beam 25 is converted into visible light 27 completely uniformly over the entire area. This is illustrated in FIG. 14 by the equal length of all arrows 27.

ADVANTAGEOUS EFFECTS OF THE INVENTION The present invention provides a luminescent screen that requires a reduced amount of emitted X-ray beam and provides high resolution.

[Brief explanation of drawings]

1, 2, 3, 4 and 5 are individual step diagrams of a method for manufacturing microstructures made of plastic, and FIGS. 6 and 7. Fig. 8, Fig. 9, Fig. 1O, Fig. 11 are manufacturing step diagrams of metal microstructures, Fig. 12, Fig. 13,
FIG. 14 shows a diagram representing the X-ray source and microstructure. l... Thick disk, 2... Substrate, 3... X-ray mask, 4... Synchrotron beam, 5...
Support with weak absorbing power, 5a, 5b...Absorber with strong absorbing power, 7,8...Shadow area by absorber, 9...P
MMA partition wall, lO...PMMA column, 11...Ninkel column, 12...gap, 13... partition wall, 14... cavity 15... partition wall, 16... cavity, 17... Luminescent substance, 19... Polyimide sheet, 20... Pillar, 21
．． 22... Gap, 23... Partition wall, 24... X-ray source, 25... X-ray beam, 26...
Point, 27... Visible light, 28... X-ray tube C ■ U-t, D ■

Claims (1)

[Claims] 1. A method for producing a luminescent screen, sensitizer and memory sheet for X-ray diagnosis, in which these members are composed of a honeycomb-like microstructure with walls and cavities. , the void space of the microstructure is filled with a luminescent material, and in the case of the above-mentioned method, furthermore, in the manufacturing method of the type in which a metal mold is repeatedly molded with a molding material, a) the metal pillar (11) is a) a high-energy beam (4) in order to produce by electroforming a mold to be provided, or b) to produce by electroforming a male mold to be provided with a metal honeycomb body (13);
A disk (1) made of a material whose properties are changed by
), by partial irradiation of the material with a high-energy beam (4) and partial removal of the material under the exploitation of the different material properties formed by the irradiation, perpendicularly or obliquely to the disk surface. Cavities (7) for forming electroformed metal molds (in case a), isolated from each other, or electroformed metal male molds (in case b), connected to each other in the form of a mesh Gap for forming (8
), and then a metal mold (11) (
In case a) or a metal male mold (13) (in case b) is formed, and then in case a) a plurality of honeycomb-shaped micro molds made of the molding material are formed by means of a fitting mold (11). In this case, the bulkhead (1
5) is made translucent by the use of a light-absorbing molding substance or by the attachment of a light-reflecting cover; in the case of b), the columnar body (20) is provided by a metal male mold (13); A plurality of temporary molds are manufactured from the molding material, and with these temporary molds, honeycomb-like microstructures (23) are manufactured from metal by electroforming using electrodes that are attached during molding. and then
In both cases a) and b), a luminescent screen, an enhancement for X-ray diagnosis, characterized in that the voids (16, 22) of a honeycomb-like microstructure are filled with a luminescent substance (17). A method for producing a memory sheet. 2. Claim 1, characterized in that a parallel synchrotron beam (4) is used to irradiate the disk (1), and furthermore, all the walls (15, 23) of the honeycomb-like microstructure are parallel. manufacturing method. 3. An X-ray tube (28) with a point-like focal spot (26a) is used to irradiate the disk (1), which also allows the line of all walls (31) of the honeycomb-like microstructure to be 1 2. The method according to claim 1, further comprising focusing on a point (26). 4. Honeycomb-like microstructure is 2 μm to 10
4. The method according to claim 2, further comprising a wall having a wall thickness of .mu.m and a cavity filled with the luminescent material having a diameter of 15 to 150 .mu.m.