JPS61162036A - Radiation picture information reader - Google Patents

Abstract

PURPOSE:To remove or a reduce a flare phenomenon generated due to the reflection of reflected excitation light at a light incident surface of a photoelectric reading means by arranging a filter between a scanning excitation light incident position on a sheet and the light incident surface of the photoelectric reading means. CONSTITUTION:The plate-like filter 15 for absorbing excitation light (reflected excitation light) reflected on the sheet 10 but transmitting accelerated phosphorescence emitting light is arranged between the position 10a of the sheet 10 upon which excitation light (scanning excitation light) 2a scanning the sheet 10 ad a condensed guide light incident surface 8a which is the light incident surface of the photoelectric reading means 7. For instance, a wavelength selecting and transmitting filter constituted so that reflected excitation light absorbed but accelerated phosphorescence emitted light is transmitted on the basis of the difference of wavelength areas between the reflected excitation light and the accelerated phosphorescence emitting light is used as the filter 15.

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) When a certain kind of phosphor is irradiated with radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.), a part of this radiation energy is emitted into fluorescent light. It is known that when this phosphor is accumulated in the body and is irradiated with excitation light such as visible light, the phosphor exhibits stimulated luminescence depending on the accumulated energy; The fluorophore is called a storage fluorophore.

Using this stimulable phosphor, radiation image information of a subject such as a human body is recorded on a -H sheet-shaped stimulable phosphor, and this stimulable phosphor sheet is scanned with excitation light such as a laser beam. The photostimulated luminescence light is read photoelectrically to obtain an image signal, and based on this image signal, a radiation image of the subject is recorded 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 it as a visible image.
No. 5-12429, No. 56-11395, etc.) In such radiation image information recording and reproducing systems, a stimulable phosphor sheet on which radiation image information is accumulated and recorded is scanned with excitation light such as a laser beam. Conventionally, a reading device as shown in FIG. 4 has been proposed for generating 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. The light enters the stimulable phosphor sheet 10 through the reflecting mirror 5 and is deflected in six directions (main scanning direction) as indicated by arrows. Optical deflector 4 and planar anti-tA mirror 5
An f.theta. lens 6 is disposed between the sheet 10 and the excitation light 2 having a uniform beam diameter and main-scanning the sheet 10 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 manner, the sheet 10 emits stimulated luminescent light with an amount proportional to the accumulated and recorded radiation energy, and this luminescent light enters the light collecting guide (light guide sheet) 8. do.

This condensing guide 8 has a linear entrance surface 8a,
It is arranged adjacent to and opposite to the scanning line 2C of the excitation light on the sheet 10, and the exit surface 8b has an annular shape and is brought into close contact with the light receiving surface of a photodetector 9 such as a photomultiplier. 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 is configured so that the light incident from the incident surface 8a is transmitted to the exit surface while being totally reflected inside. The stimulated luminescence light from the sheet 10 is guided through the condensing guide 8, exits from the exit surface, and is received by the photodetector 9.

The preferable shape, material, etc. of the condensing guide are disclosed in Japanese Patent Application Laid-Open No. 55-87.
No. 970, 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 light in the wavelength range of excitation light. It is designed to detect only light.

The stimulated luminescent light detected by the photodetector 9 is converted into an electrical signal, and after being amplified to an appropriate level electrical signal by the amplifier 11 whose sensitivity is set by the amplification factor setting value a, the
The signal is input to the D converter 12.

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 by setting an appropriate recording scale factor setting value 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. is output as a visible image to a recording material such as a CRT or a display device such as a CRT.

However, as shown in FIG. 5 when FIG. 4 is viewed from the direction of arrow C, in the conventional reading device as described above, generally,
Excitation light for scanning (hereinafter referred to as scanning excitation light) 2a incident on the sheet 10 is reflected on the sheet 10, and a part of this reflected excitation light (hereinafter referred to as reflected excitation light>2b) is used for photoelectric reading. It is reflected again at the light entrance surface (in this embodiment, the light collection guide entrance surface) 8a of the means 7 and enters the sheet 10 again, and stimulated luminescence light is emitted from that part.
A so-called flare phenomenon occurs. When this flare phenomenon occurs, the position on the surface of the sheet 10 where the reflected excitation light 2b is incident again is a position other than the pixel portion being scanned by the scanning excitation light 2a, so that the pixel being read is The photoelectric reading means 7 simultaneously reads the stimulated luminescent light emitted from the part and the stimulated luminescent light emitted from the other parts, resulting in the inconvenience that accurate image information cannot be obtained and the contrast of the image decreases. arise.

(Object of the Invention) In view of the above circumstances, an object of the present invention is to provide a radiation image information reading device that can avoid or reduce the flare phenomenon caused by re-reflection of reflected excitation light on the light incidence surface of a photoelectric reading means. It is about providing.

(Structure of the Invention) In order to achieve the above object, the radiation image information reading device according to the present invention is provided between the position where the scanning excitation light is incident on the stimulable phosphor sheet and the light incidence surface of the photoelectric reading means. , is characterized in that a filter is provided 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 light incidence surface of the photoelectric reading means means the position where the scanning excitation light is incident on the stimulable phosphor sheet. The filter is disposed at a passage position of the reflected excitation light reflected from the position where the scanning line is present toward the light incidence surface of the photoelectric reading means, and the reflected excitation light is absorbed by the filter to read the charge. This means that the light is configured so that the light does not enter the light incident surface of the means.

1 (Effects of the Invention) The radiation image information reading device according to the present invention has the following effects as described above.
A filter that absorbs the reflected excitation light but transmits the stimulated luminescence light is disposed between the scanning excitation light incident position on the sheet and the light incidence surface of the photoelectric reading means, so that the light of the photoelectric reading means described above is It is possible to avoid or reduce the flare phenomenon caused by the re-reflection of the reflected excitation light on the incident surface, and the contrast of the image can be improved.

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 light incidence surface of the photoelectric reading means, the reflected excitation light is absorbed by the photoelectric reading means. It is possible to prevent the reflected excitation light from entering the light entrance surface, and therefore prevent the reflected excitation light from being re-reflected by the light entrance surface of the photoelectric reading means and re-entering onto the sheet.
As a result, it is possible to avoid or reduce the flare phenomenon caused by the re-reflection of the reflected excitation light on the light incidence surface of the light N reading means.

(Practical 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 reading device according to the present invention, and FIG. 2 is a side view showing an enlarged main part of the device shown in FIG. FIG. 3 is a side view showing another arrangement of the filter.

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 part, 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 FIG. 1 and FIG.
an excitation light source 1 (not shown in FIGS. 1 to 3) that emits a
It consists of: The photoelectric reading means 7 consists of a condensing guide 8 and a photodetector 9, and the condensing guide 8 has a light incident surface 8.
a is located at the incident position W of the excitation light 2 on the sheet 10 (the position where the scanning line 2C exists) 10afl.

Furthermore, the illustrated apparatus has excitation light (
Position 10a where the scanning excitation light) 2a is incident on the sheet 10
and the condensing guide light incidence surface 8a, which is the light incidence surface of the photoelectric reading means 7, is a plate that absorbs the excitation light reflected on the sheet 10 (reflected excitation light) but transmits the stimulated luminescence light. A filter 15 of the shape of the shape is arranged.

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, the wavelength of reflected excitation light is 633 nm, and the wavelength of stimulated emission light is 390 nm.
For example, a filter with filter number B-390 manufactured by Hoya Glass that is used in the case where the wavelength is 100 nm is used. Of course, the absorption of the reflected excitation light and the transmission of the stimulated luminescence light by the filter 15 do not necessarily have to be 100% absorption or transmission.

The filter 15 prevents the reflected excitation light 2b reflected from the scanning excitation light incident position 10a toward the light incidence surface 8a of the direct photoelectric reading means from entering the incidence surface 8a. The reflected excitation light 2b
It is possible to avoid or reduce the flare phenomenon caused by.

The manner in which the filter 15 is arranged is not limited to the manner in which the filter 15 is disposed at a constant distance from the light incident surface 8a of the photoelectric reading means as shown in FIGS. It is also possible to adopt a mode in which it is disposed directly in close contact with the light entrance surface 8a.

In each of the embodiments described above, the filter 15 is configured such that the filter 15 absorbs all the reflected excitation light reflected in the direction of incidence on the light incidence surface 8a of the photoelectric reading means.
over almost the entire length of the light incidence surface 8a.
However, in some cases, the light incident surface 8a may be disposed opposite to or in close contact with only a portion of the light incident surface 8a.

In addition, 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 the light efficiency may be reduced to some extent, in the case of such a filter, for example in the embodiments shown in FIGS. 1 and 2, the filter is configured to be movable up and down; If the reduction of the flare phenomenon is more important for diagnosis than the light collection efficiency by moving the image upward to avoid interference with the stimulated luminescence light, for example, near the part of the sheet outside the subject where the most radiation has entered. Only when a slight difference in contrast is important, such as when diagnosing a tumor affecting the body or microcalcifications in mammography, the filter is moved downward and the light enters the light incident surface of the photoelectric reading means. Even if the reflected excitation light is absorbed, the inspection excitation light incidence position 10a and the light incidence surface 8 of the photoelectric reading means
In other words, the filter 15 absorbs only the reflected excitation light reflected toward the light incidence surface 8a of the photoelectric reading means out of the excitation light reflected from the scanning excitation light incidence position 10a. It is arranged like this. however,
The filter 15 in the present invention only needs to be disposed in such a manner that it can absorb at least the reflected excitation light reflected from the scanning excitation light incidence position 10a toward the light incidence surface 8a. If re-reflection of the reflected excitation light by other parts of the photoelectric reading means other than the surface 8a or components of the reading device other than the photoelectric reading means becomes a problem, scan the excitation light roughly toward such parts. It is also possible to arrange the scanning excitation light in such a manner that it can also absorb the reflected excitation light reflected from the incident position 10a.
It is also possible to arrange it in such a manner that it can also absorb reflected excitation light that is reflected from 0a, re-reflected by some member, and enters the light entrance surface 8a.

[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 Fig. 3 is another arrangement of the filter. Figure 4 showing aspects
5 is a perspective view showing a conventional reading device, and FIG. 5 is a side view showing a main part of the device shown in FIG. 4, and also a diagram showing the state of reflection of excitation light. 1... Excitation light source 2... Excitation light 7...
・Photoelectric reading means 8a...Light incidence surface 10 of the photoelectric reading means...Storage phosphor sheet 15...Filter

Claims (1)

[Scope of Claims] An excitation light source that emits excitation light that scans a stimulable phosphor sheet that stores and records radiation image information, and stimulated luminescence light that is emitted from the stimulable phosphor sheet by scanning with the excitation light. A radiation image information reading device comprising a photoelectric reading means for photoelectrically reading the stimulable phosphor sheet, a position where the excitation light scanning the stimulable phosphor sheet is incident on the sheet, and a light incidence surface of the photoelectric reading means. A radiation image information reading device characterized in that a filter is disposed between the sheets, which absorbs the excitation light reflected on the sheet but transmits the stimulated luminescence light.