JPH0556491B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a radiation image information reading device used in a radiation image information recording and reproducing system.

(Technical Background of the Invention and Prior Art) Certain phosphors are exposed to radiation (X-rays, α-rays, β-rays,
When irradiated with γ-rays, electron beams, ultraviolet rays, etc., a portion of this radiation energy is accumulated in the phosphor, and when this phosphor is irradiated with excitation light such as visible light, it It is known that phosphors exhibit stimulated luminescence, and phosphors exhibiting this property are called stimulable phosphors.

Using this stimulable phosphor, radiation image information of a subject such as a human body is recorded on a sheet of stimulable phosphor, and this stimulable phosphor sheet is scanned with excitation light such as a laser beam. The resulting photostimulated luminescence is read photoelectrically to obtain an image signal, and based on this image signal, a radiation image of the subject is made visible on a recording material such as a photographic light-sensitive material, a CRT, etc. The applicant has already proposed a radiation image information recording and reproducing system that outputs the information as an image. (JP-A-55-12429, No. 56-11395, etc.) In such a radiation image information recording and reproducing system, a stimulable phosphor sheet on which radiation image information is stored is exposed to excitation light such as a laser beam. Conventionally, a reading device as shown in FIG. 4 has been proposed for scanning to generate stimulated luminescence light and photoelectrically reading the obtained stimulated luminescence light.

In the illustrated apparatus, excitation light 2 is emitted from an excitation light source 1, the beam diameter of this excitation light 2 is strictly adjusted by a beam expander 3, and the beam diameter of this excitation light 2 is strictly adjusted by an optical deflector 4 such as a galvanometer mirror. A stimulable phosphor sheet 10 is passed through a flat reflecting mirror 5.
The light is deflected upward in the direction of arrow A (main scanning direction) and is incident. An fθ lens 6 is disposed between the optical deflector 4 and the plane reflecting mirror 5, and the excitation light 2 is directed onto the sheet 10.
has a uniform beam diameter and is scanned at a constant speed. The sheet 10 is conveyed, for example, in the direction of the arrow B to perform sub-scanning, and as a result, the entire surface of the sheet 10 is irradiated with excitation light. When the excitation light 2 is irradiated in this way,
The sheet 10 generates stimulated luminescent light in an amount proportional to the radiation energy stored and recorded, and this luminescent light enters the light collecting guide (light guide sheet) 8. The light condensing guide 8 has a linear entrance surface 8a and is disposed adjacent to and opposite to the scanning line 2c of the excitation light on the sheet 10, and an exit surface 8b is annular and allows light such as photomal It is brought into close contact with the light receiving surface of the detector 9. The light collecting guide 8 and the photodetector 9 constitute a photoelectric reading means 7. The light collecting guide 8 is made by processing a transparent thermoplastic resin sheet such as acrylic resin, and has an incident surface 8a.
The structure is such that the light incident on the sheet 10 is transmitted to the exit surface while being totally reflected inside the sheet 10, and the stimulated luminescence light from the sheet 10 is guided through the condensing guide 8.
The light is emitted from the exit surface and is received by the photodetector 9. The preferred shape, material, etc. of the condensing guide are given in JP-A-Sho.
It is disclosed in No. 55-87970, No. 56-11397, etc.

A filter (not shown) is attached to the light receiving surface of the photodetector 9, which passes only light in the wavelength range of stimulated luminescence light and cuts out light in the wavelength range of excitation light.
It is designed to detect only stimulated luminescence light.
The stimulated luminescence light detected by the photodetector 9 is converted into an electrical signal, and after being amplified to an electrical signal of an appropriate level by the amplifier 11 whose sensitivity is set by the amplification factor setting value a, the stimulated luminescence light is converted to an electrical signal. 12 is input.
In the A/D converter 12, the amplified electrical signal is converted into a digital signal with a scale factor suitable for the signal fluctuation width using an appropriate recording scale factor setting value b selected in advance according to the image of the subject. .
The output signal of this A/D converter 12 is input to a signal processing circuit 13, where signal processing is performed so as to obtain a radiation image excellent in suitability for observation and interpretation. output as a visible image to a recording material such as a CRT or a display device such as a CRT.

The above-mentioned reading device is generally provided with a reflecting mirror 14 as shown in the figure in order to improve the condensing efficiency of the stimulated luminescence light emitted from the sheet 10 by scanning the excitation light and obtain a high-quality image. This reflecting mirror 14 is disposed on the opposite side of the condensing guide 8 with respect to the scanning line 2c of the excitation light on the sheet 10, and the condensing guide 8 out of the stimulated luminescence light emitted by scanning the excitation light is The light directed toward the opposite side is reflected toward the condensing guide 8.

However, as shown in FIG. 5 when FIG. 4 is viewed from the direction of arrow C, in the above reading,
Generally, the excitation light 2a for scanning incident on the sheet 10 (hereinafter referred to as scanning excitation light) is
0 and this reflected excitation light (hereinafter referred to as
The reflected excitation light) 2b is reflected again by various components of the reading device (reflection mirror 14, condensing guide entrance surface 8a, other components, etc.) and is reflected onto the sheet 10.
The so-called flare phenomenon occurs in which stimulated luminescence light is emitted from that part. When this flare phenomenon occurs, the position on the surface of the sheet 10 where the reflected excitation light 2b enters again is the scanning excitation light 2a.
Since the position is other than the pixel part being read by scanning, both the stimulated luminescent light emitted from the pixel part being read and the stimulated luminescent light emitted from other parts are simultaneously detected by the photoelectric reading means. 7, resulting in the inconvenience that accurate image information cannot be obtained and the contrast of the image is also reduced.

Particularly, in the reading device provided with the reflecting mirror 14 as described above, the reflecting mirror 14 is one of the major causes of the flare phenomenon. This is because the reflecting mirror 14 reflects the stimulated luminescence light toward the light collection guide 8 to improve light collection efficiency, but at the same time it also reflects the excitation light well, so the sheet 1
The reflected excitation light 2b reflected from above the zero surface is reflected by this reflection mirror 14 and reaches the light incidence surface 8 of the condensing guide.
This is because the light is incident on a portion of the sheet 10 other than the reading pixels after being reflected again on the light incident surface 8a.

(Object of the Invention) In view of the above circumstances, an object of the present invention is to improve the efficiency of collecting stimulated luminescence light by a reflecting mirror, and to avoid or reduce the flare phenomenon caused by the reflecting mirror. The purpose of the present invention is to provide a radiation image information reading device that can read images.

(Structure of the Invention) In order to achieve the above object, the radiation image information reading device according to the present invention has a structure in which the scanning excitation light is provided between the position where the scanning excitation light is incident on the stimulable phosphor sheet and the reflecting mirror.
The device is characterized by a filter that absorbs reflected excitation light but transmits stimulated luminescence light.

Placing the above-mentioned filter between the position where the scanning excitation light is incident on the stimulable phosphor sheet and the reflecting mirror means that the position where the scanning excitation light is incident on the stimulable phosphor sheet (where the scanning line is The above-mentioned filter is disposed at a passage position of the reflected excitation light reflected from the existing position) toward the reflection mirror, and the filter is configured so that the reflected excitation light is absorbed by the filter and does not enter the reflection mirror. That is what it means.

(Effects of the Invention) As described above, the radiation image information reading device according to the present invention scans a filter that absorbs reflected excitation light but transmits stimulated emission light, and aligns the excitation light incident position on the sheet with the reflection mirror. Since the excitation light is disposed between the reflection mirror and the photoelectric reading means, it is possible to prevent the excitation light re-reflected by the reflection mirror from entering the photoelectric reading means, and as a result, the flare phenomenon caused by the reflection mirror described above can be avoided or The contrast of the image can be improved, and the incidence of the stimulated luminescence light on the reflecting mirror and the incidence of the stimulated luminescence light reflected by the reflecting mirror on the photoelectric reading means are not affected at all. Since the light is not obstructed, it is possible to simultaneously improve the light collection efficiency of the reflecting mirror.

That is, since the filter absorbs the reflected excitation light, by disposing the filter between the scanning excitation light incident position on the sheet and the reflection mirror, the reflected excitation light is prevented from entering the reflection mirror. Therefore, it is possible to prevent the reflected excitation light from being reflected by the reflecting mirror and entering the photoelectric reading means, and as a result, it is possible to avoid or reduce the flare phenomenon caused by the reflecting mirror, and
Furthermore, since the above-mentioned filter allows the stimulated luminescence light to pass through, the presence of the filter does not impede the stimulating function of the reflecting mirror to condense the stimulated luminescence light.
Therefore, the efficiency of collecting stimulated luminescence light can also be improved at the same time.

(Embodiments) Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

FIG. 1 is a plan view showing an embodiment of the device according to the present invention in which a filter is disposed between the scanning excitation light incident position and the reflecting mirror, and FIG. 2 is a main part of the device shown in FIG. 1. FIGS. 3A to 3D are side views showing other arrangement configurations of the filter, respectively.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 3. This embodiment has the same configuration as the conventional example shown in FIG. 4 except for the filter portion, which is the main part of the present invention. Therefore, such identical components are given the same numbers as in FIG. 4, and detailed explanations are omitted.

The apparatus shown in FIGS. 1 and 2 includes an excitation light source 1 (not shown in FIG. 1) that emits excitation light 2 that scans a stimulable phosphor sheet 10 on which radiographic image information is stored and recorded; A photoelectric reading means 7 that collects and photoelectrically reads the stimulated luminescence light emitted from the sheet 10 by scanning with the excitation light 2;
10a (position where c is present) and a reflecting mirror 14 that reflects stimulated luminescence light toward the photoelectric reading means 7.

Further, the illustrated device is arranged between a position 10a where excitation light (scanning excitation light) 2a that scans the sheet 10 is incident on the sheet 10 and a reflection mirror 14, and an excitation light (reflected excitation light) reflected on the sheet 10. A plate-shaped filter 15 is disposed that absorbs the light) but transmits the stimulated luminescent light.

The filter 15 may be a wavelength selection filter configured to absorb the reflected excitation light but transmit the stimulated emission light based on the fact that the wavelength range of the reflected excitation light and the stimulated emission light are different, for example. Transmission filters can be used. As a specific example of such a filter, for example, if the wavelength of the reflected excitation light is
633nm, and the filter number B made of Hoya glass is used when the wavelength of stimulated luminescence light is 390nm.
One example is a filter called -390. Of course, the absorption of the reflected excitation light and the transmission of the stimulated emission light by the filter 15 do not necessarily have to be 100% absorption or transmission.

In the case of the type shown in FIGS. 1 and 2, the manner in which the filter 15 is arranged is not limited to the manner in which the filter 15 is arranged at a constant distance from the reflecting mirror 14 as shown in those figures; A mode in which the mirror 14 is disposed in close contact with the entire front end face of the mirror 14 including the curved reflective surface as shown in a, a mode in which the mirror is disposed in close contact only with the curved reflective surface as shown in FIG. It is also possible to adopt a mode in which the light source is not brought into close contact with the curved reflective surface but is placed close to the curved reflective surface while remaining flat, or a mode in which the light source is placed in close contact with the entire linear reflective surface as shown in Figure 3(d). .

In each of the embodiments described above, the filter 15 is provided over almost the entire length of the reflecting mirror 14 so that all the reflected excitation light reflected in the direction of incidence on the reflecting surface of the reflecting mirror 14 can be absorbed by the filter 15. The reflection mirror 14 is arranged opposite to or in close contact with the mirror 14, but in some cases, the reflection mirror 1
They may be disposed facing only a portion of 4 or in close contact with each other.

Furthermore, among various filters, there are some that do not have very good photostimulated luminescence light transmittance, and filters that reflect a small amount of stimulated luminescent light on the surface of the filter. Since it is conceivable that the light efficiency will decrease to some extent, in the case of such a filter, for example in the embodiment shown in FIG. In cases where reducing the flare phenomenon is more important for diagnosis than light collection efficiency by avoiding interference with stimulated luminescence light, for example, tumors located outside the subject near the sheet area where a large amount of radiation has entered. Only when a slight contrast difference is important, such as when diagnosing microcalcifications in mammography, the filter is moved downward and the reflected excitation light is incident on the light incidence surface of the photoelectric reading means. You may also try to absorb it.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the reading device according to the present invention, FIG. 2 is a side view showing an enlarged main part of the device shown in FIG. 1, and FIGS. 4 is a perspective view showing a conventional reading device, and FIG. 5 is a side view showing the main parts of the device shown in FIG. 4, and also shows the state of reflection of excitation light. It is a diagram. DESCRIPTION OF SYMBOLS 1...Excitation light source, 2...Excitation light, 7...Photoelectric reading means, 10...Storage phosphor sheet, 14...
Reflection mirror, 15...filter.

Claims (1)

[Scope of Claims] 1. An excitation light source that emits excitation light that scans a stimulable phosphor sheet that stores and records radiation image information, and stimulated luminescence that is emitted from the stimulable phosphor sheet by scanning with the excitation light. a photoelectric reading means for condensing light and reading it photoelectrically; and a photoelectric reading means disposed near a position where the excitation light is incident on the stimulable phosphor sheet and reflecting stimulated luminescent light toward the photoelectric reading means. In a radiation image information reading device comprising a reflecting mirror, the excitation light scanning the stimulable phosphor sheet is reflected on the sheet between a position where the excitation light is incident on the sheet and the reflecting mirror. A radiation image information reading device characterized in that a filter is provided that absorbs the excitation light but transmits the stimulated luminescence light.