JPH07119838B2 - Sensitivity-compensating radiation image conversion screen for dual-sided chest radiography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a radiation image conversion screen for both chest positive side dual-sided photographing and sensitivity compensation type (hereinafter, referred to as “chest normal”) on which a front image and a side image of the chest can be readably read. "Side-sensitive dual-purpose sensitivity compensation image conversion screen").

[Conventional technology]

Radiation image conversion screen (hereinafter referred to as "image conversion screen"
Is used, for example, as an intensifying screen, a fluorescent plate, and a storage-type radiation image converter, and is used to convert an X-ray image of a subject into a visible image for the purpose of medical diagnosis and nondestructive inspection of substances. There is.

These image conversion screens basically consist of a support such as paper or synthetic resin, and a fluorescent layer provided on at least one side (possibly both sides) of the fluorescent layer. A fluorescent substance that emits high-luminance instantaneous light when excited, or X
After irradiation with visible light or infrared light, it has a constitution in which a fluorescent substance for X-rays, such as a stimulable fluorescent substance which exhibits high intensity stimulated emission upon irradiation, is dispersed in a binder. . Furthermore, the surface of the phosphor layer is optionally protected by a transparent protective film of cellulose acetate, cellulose acetate butyrate, polyethylene terephthalate or the like.

By the way, in recent years, in diagnosing a chest disease by X-ray photography, it has become necessary to perform a diagnosis not only of the lung field but also of the trachea and bronchus (that is, the hilum) overlapping the thoracic spine and the heart. However, the conventional general image conversion screen is designed to have uniform sensitivity in the same plane,
Even if the chest is photographed using this, the lung field with greatly different X-ray transmittance, and the trachea and bronchus (hilar) superimposed on the thoracic vertebra and the heart can be recorded with a suitable degree of blackening. It is difficult to visualize on a recording medium. That is, a chest X-ray image shows an X-ray image of the trachea and bronchus (hilar) that are superimposed on the thoracic vertebra and heart together with the lung field, but the X-ray transmittance for each of these organs is significantly different.
For example, when an image is taken under an X-ray exposure condition that provides an appropriate degree of darkening for the diagnosis of the lung field, the
Due to absorption of rays, the degree of blackening of the trachea and bronchus (hilum) superimposed on these organs is insufficient, and the shadows are not visible. Therefore, in order to remove such an adverse effect, the sensitivity is compared with the sensitivity of the region A including the part corresponding to the lung field as illustrated in FIG. For chest X-ray photography, the sensitivity is partially changed in the same plane so that the sensitivity of the region B including the trachea overlapped with the thoracic spine and the heart and the part corresponding to the bronchus (hilar) is increased. A sensitivity compensation conversion screen was developed and put into practical use (Japanese Patent Laid-Open No. 56-73).
400, JP-A-62-231199, etc.).

[Problems to be Solved by the Invention]

By the way, when a chest X-ray photograph is taken, it is desirable to take both a front image and a side image of the chest in order to obtain a plurality of information on the same subject. Therefore, two conventional sensitivity compensation image conversion screens for chest X-ray photography were used as intensifying screens, and the fluorescent layers were opposed to each other inside the light-tight box (cassette). In this way, when a so-called film changer is used, in which X-ray photographic film can be continuously conveyed between them, a front image is obtained when the front chest side and the chest side surface of the same subject are continuously photographed. In the case of radiography, the lung field and the trachea and bronchus (hilar) that are superimposed on the thoracic spine and heart are drawn on a piece of X-ray photographic film with an almost proper degree of blackening, but In the case of photographing, the sensitivity of the entire central portion (area B in FIG. 3) of the sensitivity compensation image conversion screen is uniformly high, and therefore, in the obtained X-ray photograph, the upper quadrant of the central portion is taken. 1 and the lower half of the blackening degree are excessive
In particular, there is an adverse effect that the degree of blackening of the portion corresponding to the posterior lower space of the mediastinum (the region from the center to the lower center of the X-ray), which is called Holtzknecht's cavity, which has low X-ray absorption, is excessive and adversely affects the diagnosis. was there.

The present invention is capable of depicting at least a lung field image, a trachea, and a bronchial (hilar) image with an almost proper degree of blackness when a front of the chest is photographed, and when the side of the chest is photographed, a posterior space of the mediastinum. It is an object of the present invention to provide a chest-side normal dual-sided sensitivity-compensated image conversion screen that does not cause shading due to excessive blackening in the area corresponding to the lower part from the center of the image to the lower part of the center of the image, which tends to interfere with interpretation.

[Means for Solving the Problems]

The chest positive side dual-purpose sensitivity compensation image conversion screen of the present invention is basically a chest positive side dual-purpose sensitivity compensation image conversion screen composed of a support and a fluorescent layer provided on the support. In the case of frontal chest imaging, a region A ₁ including a part corresponding to the lung field, a region B ₁ including a part corresponding to the upper trachea superimposed on the thoracic spine, and a part corresponding to the abdomen from the lower mediastinum has a region B ₂ which contains, thoracic and sensitivity compensating pattern consisting of areas B ₃ Metropolitan containing the portion corresponding to the superimposed trachea and bronchi (hilum) to the heart, the area
When the sensitivity a ₁ of A ₁ and 100, relative sensitivity b ₁ of the region B _1,
Relative sensitivity b ₃ of the relative sensitivity b ₂ and the region B ₃ of the area B ₂
Are in the ranges of 120 to 250, 120 to 180 and 200 to 250, respectively, and the relation of b ₃ > b ₁ ≧ b ₂ > a ₁ or b ₃ = b ₁ > b ₂ > a ₁
It is characterized by satisfying the relationship of.

Hereinafter, the method for manufacturing the chest side positive / double-sided sensitivity compensation image conversion screen of the present invention will be described in detail.

FIG. 1 exemplifies a sensitivity compensation pattern of a sensitivity compensating image conversion screen which is used on both the right side and the chest of the present invention, and the image conversion screen partially shows the sensitivity by the sensitivity compensation pattern as illustrated in FIG. It is manufactured in the same manner as the conventional sensitivity compensation image conversion screen except that it is changed.

That is, a phosphor coating solution consisting of a mixture of an X-ray phosphor, a binder resin and an organic solvent is coated on a support and dried to form a phosphor layer on the support. Polyethylene terephthalate, polycarbonate, on the surface of the phosphor layer,
Laminate a transparent thin film such as polymethylmethacrylate, or apply a resin solution obtained by dissolving a resin such as cellulose acetate butyrate, cellulose acetate, polyvinyl butyral, or cellulose acetate in a solvent onto the phosphor layer, and dry it. Method by forming a transparent protective film on the fluorescent layer, or by forming a transparent protective film as described above on a previously smooth substrate, and applying the fluorescent coating described above on it. Conventional method by applying a liquid to form a phosphor layer, peeling the phosphor layer together with the protective film, and laminating a support on the side opposite to the protective film side of the fluorescent layer. In the process of manufacturing the image conversion screen of (1), for example, (1) a method of changing the thickness of the phosphor layer according to the compensation pattern, and (2) two or more kinds of phosphor layers having different sensitivities according to the compensation pattern. Shaped with light bodies How, (3) (see Japanese above, JP-A-56-73400) a method of providing a light-absorbing layer or a light reflecting layer in accordance with the compensation pattern between the fluorescent material layer and the support layer,
(4) A method of forming a sensitivity compensation pattern layer made of a substance that absorbs the emission of the phosphor on the surface or inside of the phosphor layer (see JP-A-62-231199), (5) support and phosphor A method of dot-printing a sensitivity compensation pattern on at least one of the body layer and the protective layer using an ink in which a colorant and / or other constituents can be dissolved depending on the solvent used (JP-A-62-238500). (See the gazette)
By partially changing the sensitivity in the same plane with, for example, the sensitivity compensation pattern illustrated in FIG. 1, the chest positive side dual-purpose sensitivity compensation image conversion screen of the present invention can be manufactured. Among these methods, the relatively high sensitivity part (region B ₃ , B ₁ , B ₂ ) and the low sensitivity part (region
In order to smooth the sensitivity change at the boundary (gradation part) with A ₁ ) and make it difficult for the boundary between each area to appear in the radiographic image, the method of (5) above is used to remove the print dots near the boundary. It is more preferable to form the sensitivity compensation pattern by means such as gradually changing the content rate.

The sensitivity compensating image conversion screen for both the right side of the chest and the sensitivity compensating image conversion screen of the sensitivity compensating pattern illustrated in FIG. 1 includes an area A ₁ that includes a part corresponding to the left and right lung fields of the subject when frontal chest imaging is performed using the screen. And extends in a strip shape from the center of the upper end of the image conversion screen toward the center of the lower end. A region B ₁ including a portion corresponding to the upper part of the trachea that overlaps the thoracic vertebra, and extending in a strip shape from the lower end of the region B ₁ continuously to this region B ₁ toward the center of the lower end of the image conversion screen, A region B ₃ including a portion corresponding to the trachea and the bronchus (hilar portion) superimposed on the thoracic spine and the heart, and a region B ₃ that is continuous with this region B _3.
From the lower end of the image conversion screen to a central portion of the lower end of the image conversion screen in a trapezoidal shape, and a region B ₂ including a portion corresponding to the abdomen from the lower part of the mediastinum of the subject, and a sensitivity compensation pattern, the region B ₁ when the sensitivity a ₁ region a ₁ was 100, the relative sensitivity of the region B ₂ and the region B ₃ b _1, b ₂ and b ₃
There is in the ranges of 120～250,120～180 and 200-250, _{and, b 3> b 1> a} 1 Relationship or _{b 3 = b 1> b 2} > sensitivity setting so as to maintain the relationship of a ₁ To do. By providing a relative sensitivity distribution with such a sensitivity compensation pattern, the chest X
In the radiograph, the central part corresponding to the trachea and the bronchus (hilar) that overlap the thoracic spine in the front of the chest, which is the most important point for diagnosis in radiography, is the most sensitive, and the lower center part of the image conversion screen (lower mediastinum part of front image and abdomen part) The area that is the corresponding part
By making the sensitivity of B ₂ ) lower than that of the central part (region B ₃ ), the trachea and bronchus (hilum) superimposed on the thoracic vertebra as well as the lung field are clearly visualized in frontal chest imaging, and Even if the side of the chest is photographed using it, it is easy to have too much density on the photograph. The photodarkening degree of the part corresponding to the lower part of the Holnetskut's cavity can be kept within an appropriate range that does not interfere with interpretation. It can be used as a dual-purpose sensitivity compensation image conversion screen. When forming the sensitivity compensation pattern illustrated in FIG. 1, the width (l in FIG. 1) of the belt-shaped high-sensitivity portions of the regions B ₁ and B ₃ is the chest side positive side dual-purpose sensitivity compensation image conversion screen. It may change slightly depending on the subject to be radiographed using, but from the average value of many chest clinical X-rays, this is set to about 20 mm, and its length is in the case of a large angle size (35 cm × 35 cm) image conversion screen, From the upper end to the lower end of the image conversion screen, a region B ₁ and a region B ₃ are formed in this order with a length of approximately a quarter of the length in the vertical direction, and the region B ₂ and the region A ₁ are formed. Border, area B ₃ and area
The angles θ ₁ and θ ₂ formed by the extension of the boundary line with A ₁ are set to 7 ° to 8 ° and 20 ° to 21 °, respectively, or conversely, 20 ° to 21 ° and 7 ° to 8 °, respectively. It is preferable that the angle is °.

Further, in the manufacture of the dual-sided chest side sensitivity compensating image conversion screen of the present invention, various materials other than the above can be used as the same materials as those used in the conventional image conversion screen. That is, as a fluorescent substance for X-rays, when it is used as an intensifying screen or a fluorescent plate, CaWO ₄ , BaSO ₄ :
Pb, ZnS: Ag, (Zn, Cd) S: Ag, Gd ₂ O ₂ S: Tb, Y ₂ O ₂ S: Tb, (G
d, Y) ₂ O ₂ S: Tb, BaFCl: Eu ²⁺ , BaF ₂・ mBaCl ₂・ nKCl ・ qBaSO
₄ : Eu ²⁺ (However, 0.3 ≦ m ≦ 1.5, 0.1 ≦ n ≦ 1.0, 0.1 ≦ q
≤1.0) and other known instantaneous light-emitting phosphors can be used, and when this is used as a storage-type image converter,
BaFBr: Eu ²⁺ , BaFI: Eu ²⁺ , ZnS: Cu, Pb, BaOxAl ₂ O ₃ : Eu
Known photostimulable phosphors such as ²⁺ (however, 0.8 ≦ x ≦ 10), La ₂ O ₂ S: Eu, Sm and SrS: Eu, Sm can be used. Further, as the binder resin, any known binder resin used at the time of producing a conventional image conversion screen, such as nitrification cotton, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, urethane, etc., can be used. As the support, plastic paper such as processed paper and polyester can be used.

FIG. 2 exemplifies another sensitivity compensation pattern in the chest positive side double-sided sensitivity compensation image conversion screen of the present invention. In the chest positive side dual-purpose sensitivity compensation image conversion screen illustrated in FIG. 2, when this is used for photographing a front chest image, an area A ₁₁ that includes the portions corresponding to the left and right lung fields.
And a region B ₁₁ including a portion corresponding to the upper part of the trachea overlapped with the thoracic spine, which is sequentially formed in a band shape from the central part of the upper end of the image conversion screen toward the central part of the other end opposite to the thoracic vertebra and heart. A region B ₁₃ including a portion corresponding to the trachea and bronchus (hilar portion) overlapped with and a region B ₁₂ including a portion corresponding to the abdomen from the lower part of the mediastinum.
_When the sensitivity a ₁₁ of _{11 is set} to 100, the relative sensitivity of the above range B ₁₁
b _11, relative sensitivity b ₁₃ of relative sensitivity b ₁₂ and the area B ₁₃ in the region B ₁₂ is in the range of each 120～250,120～180 and 200-250, _{and, b 13> b 11 ≧ b} 12 ＞ Relationship of a ₁₁ or b ₃ ＞
A sensitivity compensation pattern having a relative sensitivity distribution that satisfies the relationship of b ₂ > a ₁₁ is formed. In this case, the widths of the above-mentioned areas B ₁₁ , B ₁₃ and B ₁₂ are set to about 20 mm, and their length is from the upper end to the lower end of the chest positive side dual-purpose sensitivity compensation image conversion screen in the case of a large angle size (35 cm × 35 cm). It is preferable to have sensitivity compensation patterns each having a length of ¼, ¼ and ¼ of the length in the longitudinal direction.

〔Example〕

Stick a protective film of polyethylene terephthalate film with a thickness of 12μ on a smooth substrate, and on this protective film
550nm using 300 mesh silk screen printing plate
The sensitivity compensation pattern shown in FIG. 1 was printed with an ink having the following compounding ratio containing a red oil-soluble dye having an absorption peak in the vicinity as a colorant. The halftone dot size when printing the sensitivity compensation pattern is 60 lines, and the percentage of each halftone dot in area A ₁ , area B ₁ , area B ₂ and area B ₃ is 100% (solid coating), 50%, 50%, respectively. % And 0% (no coloring), and the coloring degree between these areas is about 80 mm from the boundary line of each area toward the area with higher coloring degree (lower sensitivity) than the boundary line. The halftone dot content rate was gradually increased over this period.

Then, using a knife coater, a phosphor coating solution having the following compounding ratio on it, the fluorescent coating weight after drying is about 50 mg / c.
It was applied so that it had a size of m ^2, and dried to form a phosphor layer.

Next, the phosphor layer was peeled off from the substrate together with the protective film, and a 240 μm-thick polyethylene terephthalate support was adhered to the surface of the phosphor layer (the side opposite to the protective film side).

In this way, when the sensitivity compensation pattern shown in FIG. 1 is provided and the sensitivity of the area A ₁ is 100, the relative sensitivities of the areas B ₁ , B ₂ and B ₃ are about 150, 150 and 200, respectively. A sensitivity-compensating image conversion screen (image conversion screen [I]) which was used on both sides of the chest was obtained.

(Ink mixing ratio) 10 parts by weight of nitrified cotton Cyclohexanone 90 parts by weight DOP 1 part by weight Dye (Diaresin Red H5B, manufactured by Mitsubishi Kasei KK) 0.15 parts by weight (mixing ratio of phosphor coating liquid) Gd ₂ O ₂ : Tb Fluorescent material 200 parts by weight Nitrified cotton 15 parts by weight DOP 2 parts by weight Butyl acetate 85 parts by weight [Comparative Example 1] Using an ink and a fluorescent material coating solution having the same composition ratio as in the above-mentioned example, a thickness on a smooth substrate was obtained. A protective film of 12 μm polyethylene terephthalate film is attached, and using a silk screen printing plate on this protective film, the sensitivity compensation pattern shown in FIG. 100% (solid coating) and 0% respectively
It is (uncolored), and it is about from the boundary line toward the area A.
A sensitivity compensation in which the relative sensitivity of the area B is about 200 when the sensitivity of the area A is 100, in the same manner as in the above embodiment except that the sensitivity compensation pattern is printed by gradually increasing the halftone dot content over 80 mm. An image conversion screen (image conversion screen [RI]) was produced.

[Comparative Example 2] An ink having the same compounding ratio as that of the ink used in Comparative Example 1 and the Comparative Example 1 except that the content of the dye (Diaresin Red H5B, manufactured by Mitsubishi Kasei K.K.) was 0.03 parts by weight. Using a phosphor coating liquid similar to the phosphor coating liquid used in Example 1, the sensitivity compensation pattern shown in FIG. A sensitivity-compensated image conversion screen (image conversion screen [R-II]) with a relative sensitivity of region B of approximately 150 was produced at times.

Next, the image conversion screen [I] and the image conversion screen [R
-I] and an image conversion screen [R-II] were used to photograph a front chest image and a side view of the chest. When the image conversion screen [I] was used, the front image showed that the thoracic spine and The images of the trachea and bronchus (hilum) superimposed on the heart were clearly depicted, and the sensitivity compensation effect was fully observed. In addition, the lateral image did not show an overexposed abnormal shadow corresponding to the position of the Holzknecht cavity of the subject, which would hinder the interpretation in the lower center of the image.

On the other hand, in the case of using the image conversion screen [R-I], the trachea and bronchus (hilum) images superimposed on the thoracic vertebra and the heart together with the lung field were clearly depicted in the front chest image, but In the lateral image, the lower central part of the image, which corresponds to the position of the Holzknecht cavity of the subject, was overexposed, which hindered interpretation.

Further, when the image conversion screen [R-II] was used, the overexposure abnormal shadow was not seen in the lower center of the image corresponding to the position of the Holzknecht cavity of the subject in the chest side view, but the chest front In the image, when taken under X-ray exposure conditions so that the lung field image can be clearly drawn, the trachea and bronchus (hilum) image superimposed on the thoracic spine and heart are not clearly visible, and sensitivity compensation is not performed. It was insufficient.

〔The invention's effect〕

In the chest positive side dual-purpose sensitivity compensation image conversion screen of the present invention, when a front chest image is captured using the screen, the sensitivity is higher than that of the left and right end portions including the part corresponding to the lung field of the subject. A high-sensitivity region including a part corresponding to the upper part of the trachea of the subject, a high-sensitivity region including a part corresponding to the trachea and bronchus (hilar part of the subject) of the subject, and corresponding to the abdomen from the lower mediastinum of the subject. A high-sensitivity region including a portion is formed in this order from the central portion of the upper end of the image conversion screen toward the central portion of the lower end, and the trachea and bronchus (the hilum of the lung) of the subject located substantially in the central portion of the sensitive region are formed. The sensitivity of the area containing the part corresponding to
Since the sensitivity of the region including the part corresponding to the abdomen from the lower part of the mediastinum of the subject, which is located in the lower part of the high-sensitivity region, is increased by a predetermined ratio, the front image of the chest is photographed using this. In this case, the lung field image with greatly different X-ray transmittance, the upper trachea image superimposed on the thoracic vertebra, and the trachea and bronchial (hilar) part superimposed on the thoracic vertebra and heart are visualized on a single image. , Even when this is used for photographing the chest side view, the shadow of the part corresponding to the lower part of the Holtzknecht cavity with high X-ray transmittance, which appears in the lower center of the chest side image of the subject (prone to obstructive reading due to excessive blackening) ) Is unlikely to occur. Therefore, it is effective, for example, when it is set in a film changer or the like, and front and rear chest images are alternately and continuously photographed.

[Brief description of drawings]

FIG. 1 and FIG. 2 each illustrate the sensitivity compensation pattern of the chest side positive side dual-purpose sensitivity compensation image conversion screen of the present invention. FIG. 3 exemplifies a sensitivity compensation pattern of a conventional sensitivity compensation image conversion screen for chest X-ray photography. In the figure, A, A ₁ and A ₁₁ are low sensitivity parts, B, B ₁ , B ₁₁ , B ₂ , B ₁₂ , B ₃ , B ₁₃
Is the sensitive part.

Claims (1)

[Claims] 1. A radiographic image conversion screen for both chest normal side dual-sided photography and sensitivity compensation, which basically comprises a support and a fluorescent layer provided on the support, and in the case of front chest photography. An area A ₁ including a portion corresponding to the lung field portion, and an area B ₁ including a portion corresponding to the upper trachea superimposed on the thoracic spine,
Region B that includes the part from the lower mediastinum to the abdomen
₂ and a region B ₃ including a portion of the thoracic spine and the heart for the trachea and bronchus (hilum), and the region A _{1 has} a sensitivity a ₁ of 100. ₁ relative sensitivity b _1, the relative sensitivity b ₂ and the relative sensitivity b ₃ of the region B ₃ of the area B ₂ each 120～250,120～180
And in the range of 200 to 250, _{and, b 3> b 1 ≧ b} 2> relationship or b ₃ = b ₁ of a _1> b _2> chest positive duplex that satisfies the relationship a ₁ Sensitivity compensation type radiation image conversion screen for both photography.