JP2593232B2 - Radiation image information reader - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a radiation image information reading apparatus that reads radiation image information stored and recorded on a stimulable phosphor sheet.

<Prior art> Radiation (X-ray, α-ray, β-ray, γ-ray,
(Electron beam, ultraviolet light, etc.), the radiation energy is partially stored, and then, when the phosphor is irradiated with excitation light, such as visible light, stimulated emission according to the stored energy is performed. Is known, and a phosphor exhibiting such a property is called a stimulable phosphor (stimulable phosphor).

Using this stimulable phosphor, radiation image information of a subject such as a human body is temporarily recorded on a sheet having a layer made of a stimulable phosphor (hereinafter referred to as a phosphor sheet), and the phosphor sheet is irradiated with laser light or the like. Scans two-dimensionally with the excitation light to generate photostimulated light, and reads the photostimulated light photoelectrically to obtain an image signal. Based on the image signal, a recording material such as a photographic photosensitive material, a CRT, etc. The present applicant has proposed a radiation image information recording / reproducing system for outputting a radiation image of a subject as a visible image on a display device of Japanese Patent Application Laid-Open No. 55-1212.
Nos. 429 and 56-11395).

In such a radiation image information recording / reproducing system, reading of the phosphor sheet has been conventionally performed by various radiation image information reading devices as follows.

Radiation image information reading device (hereinafter referred to as reading device)
, The excitation light of a constant intensity emitted from an excitation light source such as a He-Ne laser is reflected and deflected in the main scanning direction by an optical deflector such as a galvanometer mirror, and is reflected through various optical elements such as an fθ lens to generate fluorescent light. The body sheet is irradiated.

This phosphor sheet is conveyed by a conveying means such as a belt conveyor or a nip roller in a sub-scanning direction substantially orthogonal to the main scanning direction. Therefore, the excitation light deflected in the main scanning direction scans the phosphor sheet two-dimensionally and entirely.

From the portion of the phosphor sheet irradiated with the excitation light, stimulated emission light corresponding to the radiation image information stored and recorded there is generated.

The stimulated emission light is directly incident on the incident surface of the light guide, or is reflected by a condensing mirror disposed opposite to the incident surface to be incident on the incident surface of the light guide, transmitted by the light guide, and excited. After passing through a filter that cuts light in the wavelength range of light, the light enters the photomultiplier tube, is photoelectrically converted into an electric signal, is subjected to signal processing, and is then reproduced as a visible image on a CRT or photographic photosensitive material. Is recorded and stored on a recording medium such as

By the way, in such a reading apparatus, one of the problems that reduces the accuracy of image reading is flare (stray light).
Problem. As the flare, various kinds of light such as invading light from the outside can be cited, but the most problematic in a reading device (radiation image information reading device) is the phosphor sheet A as shown by a dashed line in FIG. This is the excitation light that has entered and is reflected and scattered.

Some of these flares are directly reflected or scattered by the converging mirror 106 or the incident surface 104 of the light guide 102, or
Like the flares 100a and 100b, the light is reflected / scattered by the entrance surface 104 of the light guide 102 and the condenser mirror 106, or
As shown in c, the light travels in a direction substantially opposite to that of the excitation light L, is reflected and scattered by the housing of the scanning optical system, and is again incident on the phosphor sheet A to generate stimulated emission light.

The stimulating light emitted by the flare enters the light guide 102 similarly to the stimulating light emitted by the excitation light L, is transmitted, and is read as image information. However, it is extremely rare that the flare enters the same position as the irradiation position of the excitation light L, that is, the image reading position 108. Therefore, most of the stimulating light emitted by the flare is located at a position different from the position to be read. As a result, the contrast of the read image is reduced, which hinders accurate reading of image information. Further, when this reduction in contrast is processed electrically, image information due to flare is also amplified as noise, and a good image cannot be obtained when reproduced as a visible image on a CRT or various recording materials.

In order to solve such a problem, the present applicant has disclosed in Japanese Patent Application Laid-Open No. Sho 60-189736 the reflecting surface 110 of the focusing mirror 106.
A reader with a dichroic coating that reflects stimulated emission light but does not reflect excitation light
Japanese Patent Application Laid-Open No. 60-189737 discloses a reading device provided with an excitation light anti-reflection curtain that does not reflect excitation light on an incident surface 104 of a light guide. And / or a reading device in which a filter that absorbs excitation light but transmits stimulated emission light between the light guide 102 and the incident surface 110 of the light guide 102 is disclosed.

According to each of the above devices, the reflection surface 110 of the condenser mirror 106,
Alternatively, the flare reflected on the incident surface 104 of the light guide 102 and incident again on the phosphor sheet A can be greatly reduced, and the radiation image information can be read with extremely high precision compared to the conventional apparatus. it can.

<Problem to be Solved by the Invention> However, even in the device disclosed in Japanese Patent Application Laid-Open No. 60-189736, although the light intensity is small, the light transmitted through the reflective surface 110 shown by the dotted line in FIG. , Focusing mirror 106
A flare reflected by the support member 112 is generated, and cannot be removed. Also, JP-A-60-189737
In the apparatus disclosed in Japanese Patent Application Laid-Open Publication No. H11-129, the light guide 102 is usually formed of a material such as acrylic, so that high-precision dichroic coating is difficult, and flare cannot be completely removed. Further, in the apparatus disclosed in Japanese Patent Application Laid-Open No. 61-128239, it is necessary to arrange a filter near the scanning line, so that the degree of freedom in design is reduced, and a filter and its supporting member are required. The device becomes complicated.

Therefore, the appearance of an image recording apparatus with a simple configuration and further reduced flare is desired.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the related art, and it is desirable that a flare in a radiation image information reading apparatus, in particular, be reflected directly by a condensing mirror or again via another optical element to a phosphor sheet. It is an object of the present invention to provide a radiation image information reading apparatus that can significantly reduce incident flare and enable accurate reading of image information.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a scanning optical system that scans a stimulable phosphor sheet on which radiation image information is stored with excitation light, and a seed for the excitation light. A light guide for receiving and transmitting stimulated emission light emitted from the stimulable phosphor sheet by scanning with the excitation light in the vicinity of the scanning line and having an incident surface facing the scanning line; and A condensing mirror disposed in the vicinity of the scanning line so as to face the scanning line and reflect the stimulating light to be incident on the incident surface of the light guide;
A light detector that photoelectrically reads the stimulated emission light transmitted by the light guide, and a reflection surface of the light collecting mirror,
A radiation image formed by a coat film that reflects the stimulated emission light but transmits the excitation light, and a filter material that absorbs at least the excitation light is disposed on the back side of the coat film. An information reading device is provided.

The filter material for absorbing the excitation light is preferably a color filter or a light absorption filter.

Further, it is preferable that the filter material that absorbs the excitation light is a base material of the light collecting mirror or a filter disposed between the light collecting mirror and a support member of the light collecting mirror.

<Operation of the Invention> In the radiation image information reading apparatus of the present invention having the above-described predetermined configuration, the flare, in particular, the excitation light incident on the stimulable phosphor sheet and reflected and scattered is reflected by the condenser mirror, A dichroic coat film in which the reflecting surface of the condensing mirror transmits excitation light and reflects stimulated emission light, in order to prevent the light from being incident on the stimulable phosphor sheet again directly or through another optical member. Formed by Further, a filter material that absorbs the excitation light, preferably a base material of the condensing mirror is formed of a color filter material on the back side of the coat film, or the excitation light is interposed between the condensing mirror and a supporting member that supports the same. Is provided.

Therefore, in the radiation image information recording apparatus of the present invention, most of the flares incident on the condensing mirror are transmitted without being reflected by the coat film formed by the reflection surface, and furthermore, the flare of the coat film is formed. It is not absorbed by the filter material disposed on the back side and reenters the stimulable phosphor sheet to generate stimulated emission light.

Therefore, according to the radiation image information reading apparatus of the present invention, it is possible to accurately read radiation image information with less decrease in contrast and noise due to flare.

Embodiment Hereinafter, a radiation image information reading apparatus according to the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings.

FIG. 1 shows a schematic perspective view of an example of the radiation image information reading apparatus of the present invention.

The illustrated radiation image information reading device 10 (hereinafter referred to as a reading device)
Assume 10 ) Two-dimensionally scans the stimulable phosphor sheet A (hereinafter, referred to as phosphor sheet A) on which the radiation image information is accumulated and recorded with the excitation light L, and accumulates and records on the phosphor sheet A. The stimulating light is generated in accordance with the image information, and the stimulating light is photoelectrically measured to read the radiation image information recorded on the phosphor sheet A.

In the illustrated reading apparatus 10, the scanning optical system that scans the phosphor sheet A by deflecting the excitation light L in the main scanning direction indicated by the arrow a basically includes a laser light source 12, a galvanometer mirror 14, and an fθ lens. It consists of 16.

The excitation light L is emitted from the laser light source 12 and enters the galvanometer mirror 14. As the laser light source 12, various light sources such as a He-Ne laser can be used depending on the stimulable phosphor applied to the phosphor sheet A.

The excitation light L that has entered the galvanometer mirror 14 is reflected and deflected in the main scanning direction indicated by the arrow a, falls down, enters the fθ lens 16, and falls on the main scanning line 18 (see FIG. 2). The phosphor sheet A is irradiated with the focus adjusted so as to converge. The optical deflector applied to the present invention is not limited to the galvanometer mirror 20 in the illustrated example, and any known optical deflector such as a polygon mirror and a resonant scanner can be applied.

Further, it is a matter of course that various optical elements such as various surface tilt correction optical systems and mirrors for changing the optical path may be arranged in the scanning optical system of the excitation light L as needed.

On the other hand, the phosphor sheet A is placed on a belt conveyor including an endless belt 20 and rollers 22 and 24 that stretch the endless belt 20. The phosphor sheet A is conveyed by the belt conveyor in a sub-scanning direction (direction of arrow b) substantially perpendicular to the main scanning direction (direction of arrow a). Thus, the entire surface of the phosphor sheet A is two-dimensionally scanned by the excitation light L deflected in the main scanning direction.

From the position of the phosphor sheet A irradiated with the excitation light L,
The stimulated emission light corresponding to the radiation image information stored and recorded there is emitted. The stimulated emission light is distributed directly to the light guide 28 in which the incident surface 26 is arranged so as to correspond to the vicinity of the main scanning line 18 as shown in FIG. Reflected by the collecting mirror 30
The light enters the light guide 28 from 26 and is transmitted to the photomultiplier tube.
It is read photoelectrically by 32 and the result is sent to the image processing device 34.

FIG. 2 conceptually shows the vicinity of the main scanning line 18 of the excitation light L.

In the illustrated reading apparatus 10, the excitation light (hereinafter, referred to as a flare) that has entered the phosphor sheet A and is reflected and scattered again enters the phosphor sheet A to generate photostimulated light. In order to prevent this, the reflection surface 36 of the condenser mirror 30 is formed of a coat film that reflects stimulated emission light and transmits the excitation light L. Further, the base material 38 of the condenser mirror 30 It is formed by a filter material that absorbs the excitation light L.

With such a configuration, most of the flare incident on the condenser mirror 30 passes through the reflection mirror 36 without being reflected by the reflection surface 36. Further, since the flare that has passed through the reflecting surface 36 is absorbed by the base material 38, the flare is reflected by the back surface of the light collecting mirror 30 or the interface between the light collecting mirror 30 and its supporting member (not shown). Does not enter the phosphor sheet A again. Therefore, according to the reading device 10, high-precision image reading with less reading error due to flare can be performed.

As a method of forming the reflection surface 36 with a coat film that reflects the stimulating light and transmits the excitation light L, various known methods can be applied, for example, a base material made of a material such as glass. 38 illustrates a method of dichroic coating (applying a dichroic mirror) by vacuum evaporation or the like.

Further, in the reading device 10 shown in the figure,
The base material 38 is formed of a filter material that absorbs at least the excitation light L.

Examples of such a filter material include a color filter such as B410 and B390 when the wavelength of the excitation light L is 633 nm (both are HOYA
A known color filter such as a filter obtained by mixing (permeating) a color filter such as a color filter such as that manufactured by Any of the above light absorption filters can be applied. Note that the type of the filter material (the wavelength mainly absorbed by the filter material) may be appropriately set according to the excitation light L of the phosphor sheet A to be applied.

In the illustrated example, the base material 38 of the condenser mirror 30 is formed of a filter material, so that a member made of a filter material that absorbs the excitation light L is disposed on the back surface side of the reflection surface 36. The present invention is not limited to this. For example, as shown in FIG. 3, a predetermined dichroic mirror whose base material is made of a normal material such as glass plastic is applied as the condensing mirror 50, and Alternatively, a configuration may be adopted in which a filter 54 for absorbing the excitation light L is disposed between the light-collecting mirror 50 and the support member 52 of the light-collecting mirror 50.
As the filter to be applied, various filters such as an ND filter (manufactured by Fuji Photo Film Co., Ltd.) can be used as long as the filter is made of a filter material that absorbs at least the excitation light L. A light absorption filter or the like is also applicable.

Further, it is preferable to form an excitation light anti-reflection film on the incident surface 26 of the light guide 28, which transmits the stimulated emission light and absorbs the excitation light L. Although there is no particular limitation on such an antireflection film, an example is a vapor-deposited thin film of MgF ₂ , CaF ₂ , ice crystal, or the like.

The stimulated emission light incident from the incident surface 26 of the light guide 28 travels upward while repeating total reflection in the light guide 28, and the excitation light that has entered together is cut off by a color filter (not shown), and The light enters the multiplier 32 and is read photoelectrically. As described above, the electric image signal obtained here has a very small amount of stimulated emission light due to flare, and is therefore a good image signal with high contrast and little noise.

The electric signal is sent to the image processing device 34, subjected to signal processing, reproduced as a visible image on a display such as a CRT 40, or stored in an image recording medium 42 such as an optical disk.

As described above, the radiation image information reading apparatus according to the present invention has been described in detail, but the present invention is not limited to this, and various changes and improvements may be made without departing from the gist of the present invention. Of course.

<Effects of the Invention> As described above in detail, in the radiation image information reading apparatus of the present invention having the above-described predetermined configuration, among the flares generated at the time of image reading, those incident on the converging mirror are mostly reflected. Transmit this without being reflected by the surface,
Further, the light is absorbed by a filter material disposed on the back surface side of the reflection surface of the condenser mirror. Therefore, the flare does not re-enter the stimulable phosphor sheet to generate stimulated emission light.

Therefore, according to the radiation image information reading apparatus of the present invention, it is possible to accurately read radiation image information with less decrease in contrast and noise due to flare.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a radiation image information reading apparatus according to the present invention. FIG. 2 is a view conceptually showing the vicinity of a main scanning line of the radiation image information reading apparatus shown in FIG. FIG. 3 is a view conceptually showing another example near the main scanning line of the radiation image information reading apparatus shown in FIG. FIG. 4 is a view conceptually showing the vicinity of a main scanning line of a conventional radiation image information reading apparatus. Description of symbols 10: Radiation image information reading device, 12: Laser light source, 14: Galvanometer mirror, 16: fθ lens, 18, 108: Main scanning line, 20: Endless belt, 22, 24: Roller 26,104… Incoming surface, 28,102… Light guide, 30,50,106… Condenser mirror, 32… Photomultiplier tube, 34… Image processing device, 36,110… Reflective surface, 38… Base material, 40… ... CRT, 42 ... Image recording medium, 52,112 ... Support member, 54 ... Filter, A ... Storable phosphor sheet, L ... Excitation light

Continuation of the front page (56) References JP-A-60-189736 (JP, A) JP-A-60-189737 (JP, A) JP-A-61-128239 (JP, A) JP-A-60-263567 (JP) JP-A-60-156542 (JP, A) JP-A-59-15932 (JP, A) JP-A-60-46166 (JP, A) JP-A-56-11398 (JP, A) 2-217838 (JP, A) JP-A-2-235042 (JP, A) JP-A-3-44166 (JP, A) JP-A-4-3149 (JP, A)

Claims (1)

(57) [Claims] 1. A scanning optical system for scanning a stimulable phosphor sheet on which radiation image information is stored and recorded with excitation light, and an entrance surface near a main scanning line of the excitation light and opposed to the scanning line. A light guide for receiving and transmitting the stimulated emission light emitted from the stimulable phosphor sheet by the scanning of the excitation light; and a light guide arranged near the scanning line of the excitation light and opposed to the scanning line. A light-collecting mirror for reflecting stimulated emission light and entering the light-incident surface of the light guide; and a photodetector for photoelectrically reading the stimulated emission light transmitted by the light guide; The surface is formed of a coat film that reflects the stimulated emission light but transmits the excitation light, and a filter material that absorbs at least the excitation light is disposed on the back side of the coat film. Radiation image information reading device.