JPH0328799A - radiation intensifying screen pair - Google Patents

Abstract

PURPOSE:To improve the removability of a film and the ease of taking out of the film by specifying the difference (deltaRa) between the surface roughness (Ra) of the front sensitizing paper expressed by a center line average height and the surface roughness of the back sensitizing paper to >=0.3mum. CONSTITUTION:A phosphor for radiation sensitization which exhibits the light emission of a visible light region or near UV region by receiving the irradiation of radiations and a binder, such as into cellulose, are first mixed and a proper volume of a solvent is added thereto to prepare a phosphor coating liquid of an optimum viscosity. Such phoshpor coating liquid is applied on a base consisting of paper, plastic, etc., by a roll coater or the like and is dried to form the phosphor layer. A protective film consisting of a transparent film of for example, polyethylene terephthalate, etc., is formed on the phosphor layer. This sensitizing paper is provided with the ruggedness by passing the paper along a metallic roll so as to come into contact with the rugged surface thereof. The surface roughness thereof is specified to >=0.3mum difference (DELTARa) in the center line average height (Ra) between the surface of the front sensitizing paper and the surface of the back sensitizing paper constituting the sensitizing paper pair when the surface roughness is expressed by the center line average height (Ra).

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a radiation intensifying screen pair (hereinafter referred to as "intensifying screen pair")
Regarding. More specifically, the present invention relates to an intensifying screen pair that has improved peelability from a photographed X-ray photographic film (hereinafter referred to as "film") and improved ease of taking out the photographed film from a cassette (photograph frame).

(Prior art) Radiation intensifying screens (hereinafter referred to as "intensifying screens") are used for medical X-ray photography such as X-ray photography for the purpose of medical diagnosis, and industrial radiation for the purpose of non-destructive testing of materials. It is used in close contact with a film in order to improve the sensitivity of the imaging system in radiography in various fields such as radiography. This intensifying screen basically has a support such as paper or plastic, and a phosphor layer provided on one side of the support. A transparent protective film such as a polyethylene terephthalate or cellulose acetate film is generally provided on the surface. When taking radiographs, two intensifying screens are used: a front intensifying screen (the intensifying screen placed on the side closer to the radiation source) and a back intensifying screen (the intensifying screen placed on the side farther from the radiation source). As a pair of intensifying screens, when the back cover of the cassette is closed, the surface of each intensifying screen (the surface opposite to the support side, that is, the surface from which emitted light is extracted; in this specification, this surface is referred to as Place the front intensifying screen on the inner surface of the front panel of the cassette and the back intensifying screen on the inner surface of the back cover of the cassette so that the two sides (referred to as the surfaces of the intensifying screens) face each other. It is used by holding and supporting the film in between.

(Problem to be Solved by the Invention) In recent years, when developing exposed film stored in a cassette, the cassette is placed in a film opener that is connected to an automatic developing machine installed in a bright room. A bright room processing system has been developed and put into practical use that automatically takes out the film from the cassette and transports it to an automatic processor, where it is developed. and,
In such an automatic development system, when taking out the film from the cassette, (a) open the back cover upward while holding the front plate of the cassette horizontally with the front side of the cassette facing down; There is a method to remove the film inside the cassette that remains on the paper or has fallen onto the intensifying screen on the front panel using a suction cup, and (b) to hold the front panel horizontally with the front panel of the cassette facing up. The method used is to open the back cover downward and let the film inside the cassette fall under gravity and take it out.

However, conventional intensifying screens do not have sufficient peelability from the film that was in close contact with the intensifying screen in the cassette during shooting, and when trying to remove the film that has been shot using the system described above, it is difficult to remove the film. It often happens that the intensifying screen comes into close contact with either the front intensifying screen surface or the back cover side intensifying screen surface of the cassette. When removing the film using method (a) above, there will not be much of a problem if the film is in close contact with the surface of the intensifying screen on the front side of the cassette, but if the film is in close contact with the surface of the intensifying screen on the back cover side, the film will Because the film does not naturally fall onto the front intensifying screen or takes a relatively long time to fall, trouble occurs when the film is sucked and taken out using a suction cup. In addition, when taking out using the method described above, it is inconvenient to have strong contact with the intensifying screen surface on either the front plate side or the back cover side, and especially if it is in strong contact with the intensifying screen surface on the back cover side When the film is in the cassette, problems arise in that the film does not naturally fall out of the cassette, and it takes a relatively long time for the film to fall, resulting in a significant drop in work efficiency.

In order to improve the peelability between the film and the surface of the intensifying screen, attempts have been made to make the entire surface of the intensifying screen uniformly uneven, but if the degree of unevenness on the surface of the intensifying screen is increased, the film Although the releasability from the intensifying screen is improved, there is a drawback that the image quality of the intensifying screen is deteriorated.

The present invention has been made in view of the above-mentioned circumstances, and provides an intensifying screen pair that improves peelability from the film without significantly degrading the image quality and improves the ease of removing photographed film from the cassette. The purpose is to provide

(Means for Solving the Problems) The intensifying screen pair of the present invention is a combination of a front intensifying screen and a back intensifying screen, each of which has a support and a phosphor layer provided on the support. A pair of intensifying screens consisting of a centerline average roughness (R.), the difference (Δ) between the surface roughness of the front intensifying screen and the surface roughness of the back intensifying screen, Ra) is 0.3 μm or more.

The present invention will be explained in detail below.

The intensifying screen pair of the present invention consists of a combination of two intensifying screens with different surface roughness, and each intensifying screen used in the intensifying screen pair of the present invention has an arbitrary surface roughness on its surface. The screen is manufactured in the same manner as a conventional intensifying screen except that the rough surface is uniformly formed over the entire surface.

First, a radiation-sensitizing phosphor that emits light in the visible or near-ultraviolet region when irradiated with radiation is mixed with a binder such as nitrified cotton, and an appropriate amount of solvent is added to coat the phosphor with an optimal viscosity. This phosphor coating solution is applied onto a support made of paper, plastic, etc. using a roll coater, knife coater, etc., and then dried to form a phosphor layer.

Radiation sensitizing phosphor and C&:!CaWO4,
CaWO. :Pb? tungstate-based phosphor, G
Tb-activated rare earth oxysulfide phosphor such as d20■S:Tb, Y20■S:Tb, LaOBr:Tb. GdOBr
: Tb activated rare earth oxyhalide phosphor such as Tb, L
Tm-activated rare earth oxyhalide phosphor such as aOBr:Tm, LaOC:1:Tm, BaFC1:Eu2”
Divalent eurobium activated alkaline earth metal fluorohalide phosphor such as BaFBr:Eu”, ZnS:Ag,
(Zn, Cd) S: Sulfide-based phosphor such as Ag, C
sI: Tl. Additive phosphor such as Nal:T1, YTa
Any phosphor that emits light in the visible region or near ultraviolet region when irradiated with radiation can be used, including rare earth tantalate phosphors such as 04:Nb and GdTa04+Tb.

In addition to nitrified cotton, binders include cellulose acetate, ethyl cellulose, polyvinyl butyral, cotton-like polyester,
Polyvinyl acetate, vinylidene chloride-vinyl chloride copolymer, vinyl chloride-vinyl acetate copolymer, polyalkyl (meth)acrylate, polycarbonate, polyurethane, cellulose acetate butyrate, polysaccharide such as polyvinyl alcohol, gelatin, dextrin, gum arabic, etc. There are no particular limitations on the binder as long as it is conventionally known as a binder for intensifying screens.

Further, examples of organic solvents used in preparing the phosphor coating solution include ethanol, methyl ethyl ether, butyl acetate, and ethyl ether.

Note that a dispersant such as phthalic acid or stearic acid, and a plasticizer such as triphenyl phosphate or diethyl phthalate are added to the phosphor coating liquid as necessary.

The mixing weight ratio of the radiation-sensitizing phosphor and binder (in terms of solid content) in the phosphor coating solution varies depending on the combination of the phosphor and binder used, the target performance of the intensifying screen to be manufactured, etc. However, in general, it is arbitrarily selected from the range of about 2:1 to 100:1, and more preferably from the range of 8:D to 40.1.

Furthermore, the supports used in the intensifying screen used in the present invention include cellulose acetate, cellulose probionate, cellulose acetate, polyesters such as polyethylene terephthalate, polystyrene, polymethyl methacrylate, polyamide, polyimide, vinyl chloride-vinyl acetate copolymer, etc. Examples of materials used include film-formed resins such as polymer and polycarbonate, baryta paper, resin-coated paper, ordinary paper, aluminum foil, and aluminum alloy foil.

Next, if necessary, by forming a protective film made of a transparent film of polyethylene terephthalate, polyethylene, polyvinylidene helichloride, polyamide, etc. on the phosphor layer formed on the support as described above, Obtain a conventional intensifying screen.

Next, the intensifying screen obtained as described above is placed between a metal roll whose surface has been roughened by providing irregularities and a backup roll whose surface is smooth, so that the surface of the intensifying screen is the same as that of the metal roll. The intensifying screen used in the present invention is obtained by providing unevenness on the surface of the intensifying screen by passing the intensifying screen in contact with the uneven surface. At this time, the metal roll and backup roll may be heated, and the degree of surface roughness (unevenness) on the surface of the intensifying screen is determined by the amplitude of the unevenness of the metal roll, the hardness of the backup roll, and the difference between the two rolls. It can be arbitrarily adjusted by changing the pressure (linear pressure), the temperature of both rolls, the rotation speed, etc. In addition, as a method for roughening the surface of an intensifying screen, in addition to the method of passing a pre-made intensifying screen between rolls with uneven surfaces as described above, for example, A method (sandblasting method) of spraying a highly hard solid powder such as silica sand onto the surface of the intensifying screen prepared in advance as described above may be used.

In addition, in each intensifying screen used as the intensifying screen pair of the present invention, if a protective film is not provided on the surface of the phosphor layer, after forming the phosphor layer on the support, the method described above is applied. , providing irregularities directly on the surface of the phosphor layer.

In this way, several intensifying screens with different surface roughnesses were produced, and from among these intensifying screens, two intensifying screens with different surface roughnesses (front intensifying group and Select 1) (back intensifying screen) and attach it to the cassette as a pair of intensifying screens for photographing. If the surface roughness of each intensifying screen that makes up the intensifying screen pair is changed to 1, that is, the degree of surface unevenness is 6, the film peelability will improve, but the photographic image quality will be poor. If the degree of surface unevenness is reduced to 1, the peelability of the film will not be improved. Therefore, in order to minimize the problem of poor photographic image quality and to improve the peelability of the film and the ease with which photographed film can be removed from the cassette, the degree of surface roughness of each intensifying screen must be extremely high. It is preferable to use a pair of AIE intensifying screens, which are not large and have different surface roughnesses, as the front intensifying screen and the back intensifying screen.

That is, the surface roughness of the intensifying screen is, for example, JISB 06
It can be quantified by expressing the center line average roughness (R.) defined in 0H, but in the intensifying screen pair of the present invention, the peelability of the film is lower than that of the conventional one. In order to improve the ease of removing photographed film from the cassette, the surface roughness of each intensifying screen must be adjusted to JIS B.
When expressed as the centerline roughness (R.) defined by 0601, the average of the centerlines on the surface of the fan 1 intensifying screen and the surface of the back intensifying screen constituting the intensifying screen pair. The difference in roughness (R6) (△F<8) is 0.311. m or more is desirable, and when using the above-mentioned automatic phenomenon system and the above-mentioned film stacking method of (a) or (b), the sensitization that has a larger center line average roughness (R.) is preferable. It is especially good to use paper as a back intensifying screen by pasting it on the back cover side of the cassette.
Yes. In addition, in order to keep the deterioration of photographic image quality to a level that does not cause any practical problems, it is necessary to improve the center line average roughness of the front intensifying screen and the back intensifying screen that constitute intensifying screen 1. It is desirable that (R,) eventually become 3ILm or less.

In addition, in the intensifying screen pair of the present invention, the difference (ΔRa) in center line roughness (R.) on the surface of each intensifying screen is 0.31.
trn or more, one of the two intensifying screens constituting the intensifying screen pair may have a roughened surface.

Example 100 parts by weight of CaWO4 phosphor and 1 liter of vinyl chloride-acetic acid 12? Ethyl acetate was added to a mixture consisting of 8 parts by weight of Nyl copolymer (binder), etc., and thoroughly mixed in a ball mill to prepare a phosphor coating.

Next, a support made of a polyethylene terephthalate film with a thickness of 200 μm into which TiO■ powder was kneaded was prepared, and the above phosphor coating solution was applied onto this support so that the weight of the phosphor coating after drying was approximately 4 5 mg/cm2. A phosphor layer was formed by coating with a knife coater and drying.

Next, a transparent protection film made of a polyethylene terephthalate film having a thickness of about 1211 m was laminated on this phosphor layer to prepare an intensifying screen.

Next, this intensifying screen, which has unevenness on its surface, was
Between a metal roll maintained at 0'C and a backup roll with a smooth surface, place the intensifying screen in such a way that the front side is in contact with the uneven surface of the metal roll.
The intensifying screen [■1
1, and further intensifying screen [■, in the same manner as 1, intensifying screen [
I2J was produced.

Separately, the temperature of the metal roll was maintained at 95°C, and the linear pressure applied to the surface of the intensifying screen was 100 kg when passing between the metal roll with an uneven surface and a backup roll with a smooth surface. /cm except that the above intensifying screen [
■11 and intensifying screen [■, Similar to 1, intensifying screen [+. +. ] was produced, and an intensifying screen [II2] was further produced in the same manner as the intensifying screen [II, ].

Each of the paper sheets obtained in this way [■11 [I2],
The centerline average roughness (R.) on the surfaces of [IIl] and [n2] was measured by Tokyo Seimitsu K.K. K. Made by Zafco L＼55
Measured with 0A type.

Moreover, each of these intensifying screens [I1], [12]. [
II,] and [n2] to form an intensifying screen pair consisting of a front intensifying screen and a back intensifying screen as shown in the table below, and close the back cover of the cassette. Attach the front intensifying screen to the inner surface of the front panel of the cassette, and the back intensifying screen to the inner surface of the back cover of the cassette so that the surfaces of the sensitive screens face each other. After leaving it for a while, turn the front side of the cassette upside down and keep it horizontal, then turn the back cover of the cassette downwards.
The peelability of the film from the intensifying screen was measured by measuring the time it took for the film in the cassette to fall naturally when the cassette was opened to 0°.
The ease with which the photographed film could be taken out from the cassette was judged.

Furthermore, by combining these pairs of intensifying screens and a regular type film, 8
Take a radiograph test chart with 0kV x-ray,
The image quality (sharpness and graininess) of each intensifying screen was examined from the obtained X-ray photographs.

As a result, as shown in the table below, in a pair of intensifying screens, the degree of unevenness on the surface of both intensifying screens (center line average roughness Ra
) are both small and there is almost no difference between them, the intensifying screen cr, ]
The intensifying screen pair consisting of /intensifying screen [■2] had poor peelability from the film, similar to the conventional intensifying screen. In addition, the degree of unevenness (center line average roughness R.) on the surface of both intensifying screens is large, and there is almost no difference between them. ]/Intensifying screen [112] had good peelability from the film, but the sharpness was greatly reduced and the graininess was also significantly deteriorated. On the other hand, an intensifying screen consisting of intensifying screen [■1]/intensifying screen []'l,] in which the difference in the degree of unevenness (center line average roughness R.) on the surface of both intensifying screens is 07 μm. The photosensitive paper pair had good peelability from the film, and the degree of decrease in sharpness and deterioration in graininess was small.

[Note 1] Center line average roughness (Ra) is the measuring force of the stylus part 1
5 16 0.5f, cutoff value 2.5mm. Measurement length]. 2
．． Value at 5mm.

[Note 2] For peelability, when the above evaluation method is repeated j0 times, the average time until the film falls within 12 seconds is evaluated as "good peelability", and 16 seconds is evaluated as "good", and 16 seconds is evaluated as "good". Anything exceeding this was evaluated as "poor peelability" and judged as "x.1".

[Note 3] Sharpness is MTF at spatial frequency of 2 lines/mm
This is a relative value; the higher the value, the better the sharpness.

[Note 4] Graininess means that the graininess worsens in the order of ◯, △, and × as determined by visual evaluation.

(Effects of the Invention) The intensifying screen pair of the present invention is characterized in that the surface of at least one of the intensifying screens of the intensifying screen pair is roughened by providing unevenness on the surface, and the two intensifying screens have different degrees of unevenness on the surface. Since the intensifying screen pair is made of a combination of photosensitive screens, deterioration in photographic image quality (decreased sharpness and deterioration of graininess) is minimized, and peelability from the film and removal of photographed film from the cassette are improved. The performance can be significantly improved.

Claims (2)

[Claims] (1) A pair of radiation intensifying screens consisting of a combination of a front intensifying screen and a back intensifying screen each having a support and a phosphor layer provided on the support, wherein the center line average The difference (ΔR_a) between the surface roughness of the front intensifying screen and the surface roughness of the back intensifying screen, expressed as roughness (R_a), is 0.3 μm or more. Radiation intensifying screen pair. (2) The radiation intensifying screen pair according to claim 1, wherein the surface roughness of the back intensifying screen is greater than the surface roughness of the front intensifying screen.