JPH06175244A - Radiation image information reading method and device as well as radiation image conversion panel for this method and device - Google Patents

Abstract

PURPOSE:To obtain the image improved in sharpness and graininess from the image information recorded on a radiation image conversion panel. CONSTITUTION:A stretching means 15 for stretching the radiation image conversion panel 2 recorded with the radiation image, a stretching quantity detecting means 16 for detecting the stretching quantity of the panel 2 stretched by this stretching means 15 and a signal conversion section 44 for correcting an image signal in accordance with this stretching quantity are provided. The image information stretched and recorded in one direction within the plane of this panel 2 is stretched and the thickness of this panel 2 is reduced. The stretched panel 2 is irradiated with exciting light, by which the sharpness and graininess of the read image are improved. Further, the aspect ratio of the reproduced image is made the same as the aspect ratio of the original subject by subjecting this image to a reduction correction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiographic image information reading method and apparatus and a radiographic image conversion panel used in the method and apparatus, and more particularly to a high quality image with improved sharpness and graininess of a radiographic image of a subject. The present invention relates to a radiation image information reading method and apparatus capable of forming an image, and a radiation image conversion panel used in the method and apparatus.

[0002]

2. Description of the Related Art An image signal is obtained by reading a recorded radiation image, and after subjecting this image signal to appropriate image processing,
Reproduction and recording of images are performed in various fields.
For example, an X-ray image is recorded using a film having a low gamma value designed so as to be suitable for later image processing, and the X-ray image is read from the film on which the X-ray image is recorded and converted into an electric signal. By performing image processing on this electric signal (image signal) and reproducing it as a visible image on a copy photograph or the like, a reproduced image with good image quality performance such as contrast, sharpness, and graininess is obtained. (See Japanese Patent Publication No. 61-5193).

In addition, the applicant of the present invention has conducted radiation (X-ray, α
Ray, β ray, γ ray, electron beam, ultraviolet ray, etc.), a part of this radiation energy is accumulated, and when excitation light such as visible light is then irradiated, it emits stimulated emission according to the accumulated energy. Using exhaustive phosphor (storable phosphor),
Radiation image information of a subject such as a human body is once recorded on a sheet-shaped photostimulable phosphor, and the radiation image conversion panel equipped with this sheet-shaped photostimulable phosphor is scanned by excitation light such as laser light to generate a bright image. The emitted photoluminescent light is generated, the obtained photostimulated luminescent light is photoelectrically read to obtain an image signal, and a radiation image of a subject is recorded on the basis of the image signal, a recording material such as a photographic light-sensitive material, a CRT.
A radiation image recording / reproducing system for outputting a visible image to a computer has already been proposed (Japanese Patent Laid-Open Nos. 55-12429 and 56-1).
1395, 55-163472, 56-104645, 55-1163
No. 40).

This system has the practical advantage of being able to record images over a very wide radiation exposure area as compared to conventional radiographic systems using silver halide photography. That is, in the stimulable phosphor, it has been recognized that the amount of emitted light that is stimulated to emit by excitation after being accumulated is proportional to the radiation exposure amount over a very wide range, and therefore, the radiation exposure is dependent on various exposure conditions. Even if the amount fluctuates considerably, the stimulated emission light emitted from the radiation image conversion panel is converted into an electric signal by setting the reading gain to an appropriate value, and this electric signal is used to detect photographic light-sensitive materials. By outputting a radiation image as a visible image on a display device such as a recording material or a CRT, it is possible to obtain a radiation image that is not affected by fluctuations in radiation exposure.

Further, the radiation image conversion panel used for reading radiation image information in the radiation image recording / reproducing system is usually one in which the stimulable phosphor layer is coated on a support which hardly stretches, or almost stretched. It is composed of a self-supporting stimulable phosphor layer, which is a stimulable phosphor dispersed in a binder.

[0006]

By the way, from the viewpoint of diagnostic image interpretation, it is always desired that the radiation image obtained by the radiation image information recording / reproducing system or the like should have a high image quality.

In order to realize this high image quality, it is considered to increase the film thickness of the stimulable phosphor layer of the radiation image conversion panel.

That is, specifically, the thickness of the stimulable phosphor layer of the radiation image conversion panel is increased to improve the absorption amount of the irradiated radiation and be accumulated in the stimulable phosphor layer. Increase the amount of energy. According to it, the amount of stimulated emission light emitted by the excitation light irradiated in the next stage increases with an increase in the amount of accumulated energy,
It is conceivable that the contrast of the image reproduced based on the image signal obtained by condensing this stimulated emission light can be improved, and as a result, the graininess of the obtained image can be improved.

However, when the stimulable phosphor layer having the increased thickness is irradiated with the excitation light, the excitation light diffuses according to the thickness of the stimulable phosphor layer, so that the stimulable phosphor is obtained. An image signal is obtained by collecting the stimulated emission light emitted on the surface of the layer, and the image reproduced based on this image signal has a reduced sharpness, so that it is impossible to realize high image quality. Can not.

The present invention has been made in view of the above circumstances, and provides a radiation image information reading method and apparatus for improving the sharpness and graininess of an image, and a radiation image conversion panel used in the method and apparatus. The purpose is to

[0011]

According to a first radiation image information reading method of the present invention, a radiation image conversion panel in which radiation image information is accumulated and recorded is irradiated with excitation light, and by this irradiation, the radiation image conversion panel is operated. In a radiation image information reading method for photoelectrically reading emitted stimulated emission light to obtain an image signal, the radiation image conversion panel is stretchable, and the radiation image conversion panel accumulates and records the radiation image information. When irradiating with excitation light, the radiation image conversion panel may be stretched by 1% or more along at least one of two orthogonal axes in the plane of the panel to photoelectrically read an image signal. It is a feature.

The second radiation image information reading method of the present invention is the same as the first method, wherein when the radiation image conversion panel is stretched, the stretching amount of the stretched radiation image conversion panel is detected and the photoelectric conversion is performed. The image signal thus read is corrected on the basis of the detected stretched amount so that the length of the image carried by the image signal in the stretched direction becomes an appropriate length. It is a thing.

A first radiation image information reading apparatus of the present invention is an apparatus for carrying out the above radiation image information reading method, and is provided with excitation light for irradiating a radiation image conversion panel on which radiation image information is stored and recorded. In a radiation image information reading device having an excitation light source that emits light and a photoelectric reading unit that obtains an image signal by reading the stimulated emission light emitted from the radiation image conversion panel that is scanned by this excitation light, the radiation image conversion panel is The radiation image conversion panel is stretchable, and when the excitation light is applied to the radiation image conversion panel, the radiation image conversion panel is moved in the axial direction along at least one of two orthogonal axes in the panel plane. It is characterized by comprising a panel stretching means capable of stretching 1% or more of the length.

A second radiographic image information reading apparatus of the present invention is, in the first apparatus, a unit for detecting a stretching amount of the radiographic image conversion panel stretched by the stretching unit, and a photoelectric reading unit for reading. Correction means for correcting the obtained image signal on the basis of the stretching amount obtained by the stretching amount detecting means so that the length of the image carried by the image signal in the stretching direction becomes an appropriate length. It is characterized by comprising.

That is, the method and apparatus of the present invention stretches the stretchable radiation image conversion panel on which a radiation image is recorded before the stretchable radiation image conversion panel is irradiated with the excitation light, and the thickness of the panel is reduced accordingly. Of the excitation light applied to the stretched radiation image conversion panel,
While reducing the attenuation of light energy until it transmits to the back surface of this panel and increasing the light energy of the stimulated emission light emitted by this excitation light, it is possible to photoelectrically read this stimulated emission light. It is a feature.

Further, it is characterized in that the image signal obtained by the read stimulated emission light is corrected so as to correspond to the stretched magnification, if necessary.

Stretching the radiation image conversion panel when irradiating the excitation light means that at least the excitation light is irradiated from the radiation image conversion panel when the excitation light reaches the radiation image conversion panel. It means that the part is in a stretched state.

The radiation image conversion panel of the present invention is a radiation image conversion panel used in the method and apparatus for reading radiation image information, which comprises a stimulable phosphor having elasticity at room temperature and an elongation rate of 1. % Or more, and is dispersed in a binder that is stretchable.

Here, the above-mentioned extension ratio means the percentage of the extension amount due to the stretching with respect to the original length.

The term "1% or more" means that the lower limit is 1% and the upper limit is the range of elongation ratio corresponding to the maximum amount of elongation that the material can restore to its original length.

Specific examples of the binder include polyolefin, polyurethane, polyester, polybutadiene, ethylene vinyl acetate, polyvinyl chloride, natural rubber,
Fluorine rubber, polyisoprene, styrene-butadiene rubber, silicone rubber and the like are available.

The binder may be a mixture of solvents for uniformly dispersing the stimulable phosphor. Specific examples of the solvent include alcohols such as methanol, ethanol, n-propanol and n-butanol, chlorine-containing hydrocarbons such as methylene chloride and ethylene chloride, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, methyl acetate, Examples include esters of lower fatty acids and lower alcohols such as ethyl acetate and butyl acetate, ethers such as dioxane, ethylene glycol monoethyl ether and ethylene glycol monomethyl ether, and low molecular weight silicon compounds.

Further, the binder may be a mixture of a dispersant for improving the dispersibility of the stimulable phosphor and a plasticizer for improving elasticity. Examples of the dispersant include phthalic acid, stearic acid, caproic acid and lipophilic surfactants. Examples of the plasticizer include phosphates such as triphenyl phosphate, tricresyl phosphate and diphenyl phosphate, phthalates such as diethyl phthalate and dimethoxyethyl phthalate, ethyl phthalyl glycolate and butyl phthalate glycolate. There are glycolic acid esters such as rubutyl, polyesters of triethylene glycol and adipic acid, polyesters of polyethylene glycol and an aliphatic dibasic acid, such as polyesters of diethylene glycol and succinic acid.

Further, the radiation image conversion panel may be self-supporting or may be laminated with a stretchable support similar to the above-mentioned binder, and one side thereof or It may have a stretchable protective layer on both sides.

[0025]

According to the first radiation image information recording / reading method and the first device of the present invention, the stretchable radiation image conversion panel in which the radiation image of the subject is recorded in the unstretched state is excited. When irradiated with light, the radiation image conversion panel is stretched in at least one of two orthogonal axial directions, and the excitation light is irradiated in this stretched state. On the other hand, since the thickness of this panel is thinned according to the stretched magnification, when the excitation light reaches the lower layer of the stretched and thinned radiation image conversion panel, the attenuation of the excitation light is reduced. The stimulated emission light that is excited by the excitation light with a small degree of attenuation is also emitted from the surface of the radiation image conversion panel with a reduced degree of attenuation, which improves the granularity of the image to be read. To be done.

Further, the extent to which the irradiated excitation light is diffused before reaching the lower layer of the radiation image conversion panel is also reduced. Therefore, the stimulated emission light emitted from the panel due to the excitation of the less diffused excitation light is also emitted from the surface of the radiation image conversion panel with the diffused degree reduced, and thus the sharpness of the image to be read. The degree is improved.

Further, since the read image information is stretched according to the extension of the radiation image conversion panel, the number of scanning beams of excitation light per unit image information (hereinafter referred to as scanning density) is the radiation image. The conversion panel is increased at the stretched magnification as compared to the unstretched scan density.

Since this image information is an image signal having a high scanning density of the emitted excitation light as described above, the image reproduced by the recording means modulated based on this image signal is converted into this radiation image conversion. The sharpness and graininess are improved as compared with an image reproduced by using the image signal in which the image information is read in a state where the panel is not stretched.

Further, according to the second radiographic image information reading method and the second apparatus of the present invention, the vertical direction of the original subject with respect to the image signal carrying the stretched radiographic image is further enhanced. In order to obtain an image signal that bears an image that matches the ratio with the horizontal direction, the image is corrected with a reduction by the above-described stretched magnification, and an image that bears a reproduced image that has the same aspect ratio as the subject and is easy to observe. You can get a signal.

The higher the stretching ratio, the higher the scanning density can be made, and thereby the effect of improving the sharpness and graininess of the image can be increased, but the elongation rate is the radiation image conversion. When the panel exceeds the maximum expansion rate at which it can be restored to its original size, this radiation image conversion panel is not restored to its original size and cannot be used repeatedly. This maximum elongation rate varies depending on the type and particle size of the phosphor, the type of binder, the mixing ratio of the phosphor and the binder, etc., but it is possible to set it to 50% or more by selecting these. is there. If the elongation rate is 1% or more, the intended purpose is not achieved, and if it is less than 1%, the effect of improving the sharpness and graininess of the image is not recognized.

Further, since the radiation image conversion panel of the present invention is used in the method and apparatus of the present invention, it is useful for enhancing the sharpness and graininess of the radiation image.

[0032]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram showing an example of a radiation image information reading apparatus for carrying out the radiation image information reading method of the present invention. The illustrated radiation image information reading apparatus 10 conveys a radiation image conversion panel 2 in which radiation image information is accumulated and recorded and which can be stretched by 1% or more in the direction of arrow V, and
The stretching means 15 for stretching by 1% or more in the direction of the arrow V, the excitation light source 33 for emitting the excitation light 34 to be irradiated onto the panel 2 on the stretching means 15, and the excitation light 34 for the panel 2. An image reading unit 13 including an optical scanning system 31 for scanning and an image reading system 11 for photoelectrically reading the stimulated emission light emitted from the scanned panel 2 to obtain an image signal, and the image reading unit 13 In the stretched amount detecting means 16 for detecting the stretched amount of the panel 2 stretched in (1), and the image signal read and output by the image reading unit 13 according to the detected stretched amount, the image signal is corrected and then corrected. Output signal converter
The correction processing unit 22 having the reference numeral 44 is provided.

Next, the operation of this embodiment will be described.

As shown in FIG. 1, the panel 2 on which the radiation image is stored and recorded is stretched before the irradiation of the excitation light 34.
According to 15, the film is stretched in a certain uniaxial direction (panel conveying direction) by an elongation rate of 1% or more. This action will be described in detail with reference to FIG.

FIG. 2 is an operation explanatory view for explaining the operation of the stretching means 15 shown in FIG.

The stretching means 15 shown in the drawing has a first belt 15c driven by a first roller 15a which rotates in the direction of arrow F by a motor not shown, and a second roller 15b which rotates in the direction of arrow E by a motor not shown. Second driven by
Belt 15d and a pressure roller 15e.

First, as shown in FIG. 2 (A), the radiation image conversion panel 2 conveyed by the conveying means 11 to the second belt 15d is placed on the second belt 15d and then the first belt 15d.
Transported in the direction of 15c. Then pressure roller 15e and second
The panel 2 that has passed between the belt 15d and the first belt 15c driven by the roller 15a has its leading end mounted on the first belt 15c, and this leading end is fixed on the first belt 15c. It is fixed to the first belt 15c by means 15f. After the front end of the panel 2 is fixed to the first belt 15c, the first belt 15c is driven by the first roller 15a and the speed V _E is 1% or more faster than the speed V _E of the second belt 15d. Start moving in the direction of arrow V with _F (Fig. 2 (B))
reference).

By the way, the second belt of the panel 2
The portion mounted on 15d moves in the direction of arrow V at a speed V _{E due} to the frictional force between the pressure roller 15e and the second belt 15d. Therefore, the front end of this panel 2 moves at a faster speed than the rear end, so that this panel 2 is shown in FIG.
It is gradually stretched as shown in FIG.

The panel 2 stretched in this way is located near the rear end of the panel 2 on the first belt 15c immediately before the rear end of the panel 2 passes through the pressure roller 15e. It is fixed to the first belt 15c by the second panel fixing means 15g (Fig. 2 (E)) and is kept in the stretched state even after it is separated from the pressure roller 15e (Fig. 2).
(F)).

In this way, the stretching amount (difference between the original length and the length after stretching) of the radiation image conversion panel 2 fixed in the stretched state on the first belt is the stretching amount detecting means. Memory detected by 16 and converted to electrical signal
Temporarily stored at 45. A specific method of detecting the amount of stretching is, for example, a first roller 15a and a second roller 15 which drive the first belt and the second belt, respectively.
These rotational speed differences from the rotational speed with b are detected, and the rotational speed difference is multiplied by the time required for the above-mentioned stretching to obtain the above-mentioned amount of stretching, or a radiation image conversion of the original length in advance. Adopting various methods such as attaching two marks indicating the reference span to the side end surface of the panel 2 and obtaining the stretch amount directly by a photoelectric reader or the like after the stretch of the two marks after stretching. You can

FIG. 3 is a block diagram showing the details of the image reading section 13. The radiation image conversion panel 2 stretched and fixed on the first belt 15c is moved in the arrow Y direction (the same direction as the arrow V direction shown in FIG. 2) by the first belt 15c driven by the first roller 15a. Is transported (sub-scanning). On the other hand, the excitation light 34 emitted from the laser light source 33 is the motor 35.
The rotating polygon mirror 36 driven by
After being reflected and deflected by the sheet 2 and passing through a focusing lens 37 such as an fθ lens, the optical path is changed by a mirror 38 and the sheet 2
To the main scanning in the arrow X direction which is substantially perpendicular to the sub scanning direction (arrow Y direction). From the portion of the sheet 2 irradiated with the excitation light 34, the stimulated emission light 39 having a light amount corresponding to the stored and recorded radiation image information is diverged, and the stimulated emission light 39 is condensed by the light guide 40. And is photoelectrically detected by a photomultiplier 41 as a photodetector.
The analog output signal S ₀ output from the photomultiplier 41 is amplified by the amplifier 42 of the correction processing unit 15, sampled by the A / D converter 43 with a predetermined recording scale factor, and digitized to obtain the image signal S. can get.

Here, the original size of the radiation image conversion panel 2 before being stretched is L _y in the direction of conveyance as shown in FIG. 4 (A), and is orthogonal to this L _y . Assuming that the length in the direction is L _x and the stretching amount in the transport direction detected by the stretching amount detecting means 16 is ΔL _y as shown in FIG. 4 (B), the panel 2 is stretched in the transport direction. The multiplication factor is (L _y + ΔL _y ) / L _y . At this time, the original image recorded on this panel before being stretched is also an image enlarged in the carrying direction by the above-mentioned magnification (L _y + ΔL _y ) / L _y .

When optical scanning is performed on the stretched image and the original image, the number of scanning lines scanned on the stretched image is (L _y + ΔL _y ) of the number of scanning lines scanned on the original image.
/ L _y times, and the number of scanning lines per unit image information (hereinafter referred to as scanning density) can be increased. Therefore, the amount of image information that can be read is less than that of the amount of image information that can be read without stretching the panel 2. L _y + ΔL _y ) / L _y times, which can improve the sharpness of the image to be read.

On the other hand, the stretched panel 2 has a thin film thickness in the thickness direction, and the excitation light emitted can easily reach the lower layer of the panel 2. That is, because the diffusion of the excitation light is reduced, the sharpness is improved, the attenuation of the energy of the excitation light is reduced, and as a result, the intensity of the excitation light to be irradiated is substantially the same as the effect, That is, the contrast can be improved and the graininess of the image quality can be improved.

Next, the image signal S is input to the signal conversion unit 44 (see FIG. 1), and at the magnification corresponding to the amount of extension input from the memory 45, the direction in which the image carried by the image signal S extends (conveyance). A correction process for reducing the (direction) component is performed. By this correction processing, the image signal S is converted into a corrected image signal S'and is output from the signal conversion unit 44, whereby the aspect ratio is the same as the aspect ratio of the subject stored and recorded in the radiation image conversion panel 2. An image signal that carries a reproduced image can be obtained.

Next, a second embodiment will be described in which the image reading section in the above embodiment can read image information from both the front surface and the back surface of the radiation image conversion panel.

The radiation image conversion panel on which the radiation image is recorded is irradiated with excitation light, and the stimulated emission light generated by this excitation light is read separately from both surfaces of this radiation image conversion panel to obtain two substantially equal images. A system capable of improving the S / N ratio of an image by obtaining a signal and converting these two image information into a composite image signal by processing such as addition for each pixel is disclosed in Japanese Patent Laid-Open No. 55-87970. Are disclosed by

FIG. 5 is a schematic view showing another embodiment of the panel stretching means 15 shown in FIG. Panel stretching means shown
Reference numeral 19 denotes two rollers 19a and 19a having different peripheral speeds.
′ And 19b and 19b ′, rollers 19a and 19b
Both rotate in the direction of arrow Q, and rollers 19a 'and 19b
Both are rotating in the R direction opposite to the arrow Q direction.

Further, the rollers rotating in mutually opposite directions
19a and 19a 'rotate at the same peripheral velocity V ₁ ,
The rollers 19b and 19b 'rotate at the same peripheral velocity V ₂ which is faster than V ₁ by 1% or more.

The roller 19a rotating in the opposite direction to each other
19a 'supplied from the conveyance means 11 between the radiation image conversion panel 2 freely recorded stretched radiation image, the rollers 19a and 19a' are conveyed at a speed V ₁ in the direction of arrow W is crimped to the It The panel 2 conveyed in the arrow W direction is inserted between rollers 19b and 19b 'which rotate in opposite directions. Since the rollers 19b and 19b 'have a peripheral speed higher than that of the rollers 19a and 19a' by 1% or more, the portion stretched between the rollers 19a and 19a 'and the rollers 19b and 19b' of the panel 2 is The film is stretched by this speed difference.

By thus constructing the panel stretching means 19 by the rotating rollers 19a, 19a ', 19b, 19b' having a stretching action, the above-mentioned rollers of the radiation image conversion panel 2 are formed.
The radiographic images recorded on this panel 2 can be read from both sides of the stretched part between 19a and 19b,
By configuring the image reading unit 21 as shown in FIG. 6, the S / N ratio of the radiation image can be improved and the sharpness and graininess can be improved.

That is, in the image reading section 21 shown in FIG. 6, the light guide 40 and the photomultiplier 41 of the image reading section 13 shown in FIG. 1 are provided on both sides A and B of the panel 2, respectively. An image is read from each surface to obtain image information S _A and S _B , and the signals S _A and S _B are combined by the signal combining means 47 for each pixel to obtain a signal S ₀ .

This image signal S ₀ is responsible for an image having an improved S / N ratio as disclosed in Japanese Patent Laid-Open No. 55-87970 and has the same sharpness as the above embodiment. And bears an image with improved graininess.

In the above two embodiments, the radiation image conversion panel 2 is stretched only in the direction in which the panel 2 is conveyed, that is, in the uniaxial direction. However, the stretching is not limited to the above, and the stretching may be performed in each of two orthogonal axial directions.

The third embodiment described below is an example of a device for stretching the panel 2 in each of the two orthogonal axial directions. Radiation image information reading apparatus of this embodiment
Reference numeral 50 denotes a panel stretching means 15, a stretching amount detecting means 16 and a signal converting section 44 for the radiation image information reading apparatus 10 shown in FIG.
The radiation image information reading apparatus 10 has the same configuration except that

That is, the panel stretching means 17 of this embodiment is for stretching the panel 2 in the respective directions of two axes x and y which are orthogonal to each other in the plane of the panel 2, and the stretching amount detecting means 18 (FIG. 1). (Refer to FIG. 4) detects the respective stretching amounts in the x direction and the y direction of the panel 2 stretched by the panel stretching means and outputs them to the memory 45, and the signal conversion unit 46 corrects the signal conversion unit 44 of the embodiment. The processing is performed for each of the x direction and the y direction.

FIG. 7 is a plan view and a sectional view showing the panel stretching means 17 of the third embodiment. Panel stretching means shown
The reference numeral 17 indicates two sets of facing spiral rollers 17a, 17a 'and 17b, 17 having different inclination directions from the longitudinal center.
b ', two opposed first rollers 17c, 17c' having a low rotation speed, and two second rollers 17d, 17d 'having a rotation speed faster than 1% by 1% or more than the first roller Is.

According to the panel stretching means 17, the conveying means
The radiation image conversion panel 2 supplied from 11 is a spiral roller.
When passing between 17a and 17a 'under pressure, the spiral roller 17a, 17a' has a helically carved protruding shape, and the axis x of the two orthogonal axes x and y in the plane of the panel 2 is The width of the spiral roller 17a, 17a
This widening is increased by the spiral rollers 17b, 17b 'having the same shape as a'. Then smooth rollers 17c and 17c '
Between rollers 17d and 17d, which are also smooth
Enter in between

At this time, since the rotational speeds of the rollers 17d and 17d 'are higher than the rotational speeds of the rollers 17c and 17c', the panel 2 is extended in the axis y direction between the rollers 17c and 17d. That is, the panel 2 is stretched between the rollers 17c and 17d in both the x-axis direction and the y-axis direction.

The panel 2 is irradiated with the excitation light 34 between the rollers 17c and 17d stretched in the two axial directions which are orthogonal to each other in the same manner as in the above-mentioned embodiment, and the stimulated emission is read to obtain the result shown in FIG. An image signal S carrying an image K _r stretched in both directions of two orthogonal axes x and y as shown in (C).
Can be obtained.

This image signal S has a stretched orthogonal 2
Since the image information increases in each of the two axial directions, the MTF increases as in the above embodiment, and the image reproduced based on this image signal S has improved sharpness. Further, the graininess is also improved as in the above-mentioned embodiment, and the quality of the radiation image can be improved.

The image signal S thus obtained is subjected to the stretching amount Δ in the x-axis direction and the y-axis direction obtained by the stretching amount detecting means 18 by the signal converting unit 46 (see FIG. 1).
The corrected image signal S ′ is output after being subjected to the correction processing for reducing the magnification in accordance with L _x and ΔL _y , whereby the same aspect ratio as that of the subject stored and recorded in the radiation image conversion panel 2 is obtained. It is possible to obtain an image signal that carries the reproduced image of.

As described in detail above, according to the radiation image information recording / reading method and apparatus of the present invention, the sharpness and graininess of the radiation image can be improved.

The radiation image information reading apparatus of the above embodiment is
By providing the stretching amount detection means and performing the correction process, it is possible to obtain an image signal that carries a reproduced image having the same aspect ratio as the subject's aspect ratio. The invention is not limited to the one provided with the detection means, and a radiation image information reading device which does not have the above-mentioned stretching amount detection means and does not perform the above-mentioned correction processing action can be adopted. Also, the sharpness and graininess of the reproduced image can be improved.

Since the radiation image conversion panel is repeatedly used, the stretching amount is within a range that can be naturally restored to the original size after the radiation image conversion panel used is stretched. Must be one.

Next, specific examples of the radiation image conversion panel used in the method and apparatus of the present invention will be described.

Example 1 Phosphor BaFBr: Eu ²⁺ 50
0 g and a binder silicone rubber (KE108 manufactured by Shin-Etsu Chemical Co., Ltd.)
) 100 g and 5 g of the same (C108 manufactured by Shin-Etsu Chemical Co., Ltd.) are added to the solvent methyl ethyl ketone and mixed uniformly with a propeller mixer to form a stimulable phosphor layer for a radiation image conversion panel with a viscosity of 30 Ps (25 ° C). The coating liquid was adjusted. This coating solution was then fixed on a horizontal glass plate to a thickness of 25
It was coated on a temporary support made of polyethylene terephthalate having a thickness of 0 μm using a doctor blade, dried, and left to stand overnight. Then, the dried body of the coating solution left to stand all day and night was peeled off from the temporary support to give a phosphor layer thickness of 100.
Three levels of self-supporting radiographic image conversion panels varying in the range of ~ 200 μm were formed.

A tube voltage of 80 kV is applied to this radiation image conversion panel.
The panel is irradiated with p-rays and stretched in the dark to 1.1 times its original length in the dark direction without changing the horizontal length. The panel was fixed on the panel, the He-Ne laser was two-dimensionally scanned on this panel to excite the phosphor of the panel, and the stimulated emission light emitted by the excitation was photoelectrically read to obtain image information.

The modulation transfer function (M
TF), RMS granularity at a dose of 0.1 mR was measured.

The results of this measurement are shown in FIG.

(Embodiment 2) The radiation image conversion panel formed in Embodiment 1 is the same as that in Embodiment 1 except that the length in the vertical direction is 1.1 times and the length in the horizontal direction is 1.1 times. MT of image information obtained by performing the same operation
F, RMS granularity at a dose of 0.1 mR was measured.

The results of this measurement are shown in FIG.

(Comparative Example 1) The same operation as in Example 1 above is performed except that the radiation image conversion panel formed in Example 1 above is not stretched in both the vertical and horizontal directions in Example 1. M of the obtained image information
TF, RMS granularity at a dose of 0.1 mR was measured.

The results of this measurement are shown in FIG.

Example 3 Phosphor BaFBr: Eu ²⁺ 50
0 g and a binder polybutadiene (JS manufactured by Japan Synthetic Rubber Co., Ltd.)
SR-RBS20 dissolved in toluene) 500 g (however, solid weight) was added to the solvent toluene and mixed uniformly with a propeller mixer to produce a photostimulable fluorescence of a radiation image conversion panel with a viscosity of 30 Ps (25 ° C). A coating liquid for forming a body layer was prepared.

A self-supporting radiation image conversion panel having a film thickness of 2 levels was formed by the same operation as in the following examples.

A tube voltage of 80 kV is applied to this radiation image conversion panel.
The panel was irradiated with p-rays of p, and stretched vertically in the dark to 1.05 times the original length without changing the horizontal length. It is fixed to an aluminum frame and He-Ne is attached to this panel.
Two-dimensionally scan the laser to excite the phosphor of the panel,
The stimulated emission light emitted by excitation is photoelectrically read from both sides of the panel separately (for details, refer to Japanese Patent Laid-Open No. 55-87970), and two image signals read from the both sides are read for each corresponding pixel. To obtain the image information.

The modulation transfer function (M
TF), RMS granularity at a dose of 0.1 mR was measured.

The results of this measurement are shown in FIG.

(Embodiment 4) The radiographic image conversion panel formed in Embodiment 3 is the same as that in Embodiment 3 except that the length in the vertical direction is increased to 1.05 times and the length in the horizontal direction is increased to 1.05 times. Perform the same operation to obtain the image information MT
F, RMS granularity at a dose of 0.1 mR was measured.

The results of this measurement are shown in FIG.

(Comparative Example 2) The same operation as in Example 3 was performed except that the radiation image conversion panel formed in Example 3 was not stretched in both the vertical and horizontal directions in Example 3. M of the obtained image information
TF, RMS granularity at a dose of 0.1 mR was measured.

The results of this measurement are shown in FIG.

As described above, FIGS. 8 and 9 show that the sharpness and graininess of an image are improved by stretching and reading the radiation image conversion panel on which the radiation image is recorded. It was also shown that the greater the degree of stretching of this panel, the more improved the sharpness and graininess of the image.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an example of a radiation image information reading apparatus according to the present invention.

FIG. 2 is an operation explanatory view for explaining the operation of the panel stretching means 15 shown in FIG.

FIG. 3 is a configuration diagram showing details of an image reading unit 13 shown in FIG.

FIG. 4A is a schematic diagram showing an original image read from a non-stretched radiation image conversion panel. FIG. 4B is a schematic diagram showing an image read from a radiation image conversion panel stretched in one axis direction. Schematic showing an image K _r read from a radiation image conversion panel stretched in a horizontal direction

FIG. 5 is a schematic view showing another embodiment of the panel stretching means.

FIG. 6 is a configuration diagram of an image reading unit capable of double-sided reading of a radiation image.

FIG. 7 is a plan view and a sectional view showing a third embodiment of the panel stretching means.

FIG. 8: MTF and RM of the radiation image conversion panel of the present invention
First graph showing the relationship with S granularity

FIG. 9: MTF and RM of the radiation image conversion panel of the present invention
Second graph showing the relationship with S granularity

[Explanation of symbols]

 2 Radiation image conversion panel 10,50 Radiation image information reading device 11 Image reading system 13,21 Image reading unit 15,17,19 Panel stretching means 16,18 Stretching amount detecting means 22 Correction processing unit 31 Optical scanning system 33 Laser light source 34 Excitation light 40, 40 'Optical guide 41, 41' Photomultiplier 42 Amplifier 43 A / D converter 44, 46 Signal converter 45 Memory 47 Signal combining means

Claims (5)

[Claims] 1. A radiation image conversion panel on which radiation image information is stored and recorded is irradiated with excitation light, and the stimulated emission light emitted from the radiation image conversion panel by the irradiation is photoelectrically read to obtain an image signal. In the radiation image information reading method, the radiation image conversion panel is stretchable, and when the radiation image conversion panel in which the radiation image information is stored and recorded is irradiated with excitation light, the radiation image conversion panel is changed to the radiation image conversion panel. A radiographic image information reading method, characterized in that the image signal is photoelectrically read by stretching the image signal by 1% or more along at least one of two orthogonal axes in the plane of the image conversion panel. 2. When the radiation image conversion panel is stretched, the stretching amount of the stretched radiation image conversion panel is detected, and the photoelectrically read image signal is stretched in the image carried by the image signal. The radiographic image information reading method according to claim 1, wherein correction is performed on the basis of the detected stretching amount so that the length in the different direction becomes an appropriate length. 3. An excitation light source that emits excitation light for irradiating a radiation image conversion panel on which radiation image information is stored and recorded,
In a radiation image information reading device having a photoelectric reading unit that reads the stimulated emission light emitted from the radiation image conversion panel scanned by the excitation light to obtain an image signal, the radiation image conversion panel is stretchable. When irradiating the radiation image conversion panel with the excitation light, the radiation image conversion panel is provided with 1% of its axial length along at least one of two orthogonal axes in the panel plane. A radiation image information reading device comprising a panel stretching means for stretching the above. 4. A unit for detecting the amount of stretching of the radiation image conversion panel stretched by the stretching unit, and an image signal read by the photoelectric reading unit, in the stretched direction of the image carried by the image signal. 4. The radiation image information reading apparatus according to claim 3, further comprising a correction unit that corrects the length based on the stretching amount obtained by the stretching amount detecting unit so that the length becomes an appropriate length. 5. A radiation image conversion panel having a stimulable phosphor layer in which a stimulable phosphor is dispersed in a binder, wherein the binder is elastic at room temperature and has an elongation rate. Stretchable within a range of 1% or more.
Alternatively, a radiation image conversion panel used in the radiation image information reading method according to claim 2 and the radiation image information reading device according to claim 3 or 4.