JPS60189736A - Reader for radiation image information - Google Patents

Abstract

PURPOSE:To obtain an excellent reproduced image by providing an excited light reflection preventing film on the incidence end surface of a light converging body and further arranging a light converging mirror which reflects accelerated phosphorescence, but does not reflects excited light near where the excited light makes a scan. CONSTITUTION:A storage type phosphorescent material sheet 3 is irradiated with scanning laser light 1b to cause accelerated phosphorescence at the irradiated position on the sheet 3 to intensity corresponding to image information, and its emitted light is guided from the incidence end surface 4a of the light converging body 4 to a photomultiplier tube 5 through the light converging body 5 and converted into an electric signal to read the image. The excited light reflection preventing film 13 is formed on the incidence end surface 4a for the excited light 1b and the light converging mirror 10 is arranged along the scanning part while having the reflecting surface 10a opposite the incidence end surface 4a, so that the reflecting surface 10a reflects the accelerated phosphorescent light, but does not reflect the excited light. Therefore, the excited light which illuminates the sheet 3 and is reflected there is never incident on the sheet again, so accurate image information is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image information reading device in a radiation image information recording and reproducing system using a stimulable phosphor sheet.

(Prior art) A radiation image information recording and reproducing system using a stimulable phosphor sheet (hereinafter sometimes simply referred to as "sheet J") is as follows:
The applicant has carried out research and development, and has filed numerous patent applications (for example, Japanese Patent Laid-Open No. 55-12429,
JP-A-56-11395, JP-A-55-163472
issue), has been announced in various places including the Japanese Society of Radiology, and is attracting attention (for example, see Nikkan Kogyo Shimbun, June 23, 1980, issue, page 16).

This system can obtain various types of diagnostically important information that cannot be obtained with conventional X-ray photography, and can be combined with the latest medical technology such as C'T and IR imaging methods to further increase diagnostic effectiveness. It is extremely effective for medical diagnosis.

This system is broadly divided into imaging (accumulating and recording radiation images), reading (converting accumulated and recorded images into image signals, and in some cases recording and storing readout image signals), and reproduction (imaging). The present invention relates to the conversion of signals into visible images (display on CRT etc. or permanent recording on film), and the reading of this.

An example of a radiation image information reading device used in the above system is shown in FIG. 1, and the operation and problems of the device will be explained below using this figure.

A laser beam (excitation light) 1a of a constant intensity is made to enter a galvanometer mirror 2 from a laser light source 1, and the galvanometer mirror 2 directs the laser beam in the width direction of a stimulable phosphor sheet 3 placed below the galvanometer mirror 2. The laser beam is deflected and irradiated onto the sheet 3 so that it performs main scanning (scanning in six directions of arrows). Further, the sheet 3 is attracted onto, for example, an endless belt device 9 and conveyed (sub-scanned) in the direction of arrow B, so that the main scan is repeated at an angle substantially perpendicular to this sub-scan, and the entire surface of the sheet 3 is Two-dimensional scanning is performed by the laser beam 1b over the entire area. Therefore, according to the scanning by the laser beam 1b, the laser beam 1b
The irradiated area of the sheet emits stimulated light with an intensity corresponding to the accumulated and recorded image information, and this emitted light is collected by a transparent condenser near the sheet whose incident end surface 4a is arranged parallel to the main scanning line. The light enters the light condenser 4 from the incident end face 4a of the body 4. A condensing mirror is provided opposite to the incident end surface 4a and has a surface parallel to the main scanning direction, and the stimulated luminescence light emitted toward the condensing mirror 10 is directed toward the incident end surface 4a. By reflecting the light, the light collecting efficiency of the light collecting body 4 is improved. The light condenser 4 has a flat front end 4b located near the sheet 3, and gradually becomes cylindrical toward the rear end, and has a substantially cylindrical shape at the rear end 4G. Since it is coupled with the photomultiplex 5, stimulated luminescence light entering from the incident end surface 4a is efficiently collected at the rear end 4C and transmitted to the photomultiplex 5. A filter (not shown) is provided at the joint between the rear end portion 4C and the photomultilayer 5 to allow the stimulated luminescence light to pass through as is, but to absorb the excitation light, which is irradiated onto the sheet 3 and reflected there. to prevent passage of excitation light entering the condenser. Therefore, only the stimulated and emitted light is transmitted to the photomultiplex 5, where the stimulated emitted light is converted into an electrical signal and then sent to the image information reading circuit 6. The electrical signal is processed and outputted by the image information reading circuit 6, and can be output as a visible image on a CRT 7 or recorded on a magnetic tape 8, for example.

In the radiation image information reading device configured as described above, when scanning the sheet 3 with the laser beam (excitation light) 1b, the laser beam 1b irradiated onto the sheet 3 is reflected by the sheet 3 and is emitted from the condenser. The light enters the incident end surface 4a and the condensing mirror 1o of 4, and further the incident end surface 4a and the condensing mirror 1o.
There is a problem in that the laser beam 1b is reflected by the laser beam 0 and hits a portion of the sheet 3 other than the portion irradiated with the laser beam 1b, causing this portion to undergo stimulated luminescence. If a portion other than the area irradiated with the laser beam 1b emits photostimulated light, this stimulated emitted light is collected by the condenser 4 together with the light that has been stimulated by direct heat tJJ of the laser beam 1b, and is converted into laser light. Since the image information is processed as image information from the irradiated portion of 1b, there is a problem that the resulting reproduced image will be inaccurate.

For example, consider the laser beam 1G at a certain moment during scanning by the laser beam 1b in FIG. 1 as an example.

The points 3a on the seas 1 to 3 that are irradiated with the laser beam 1C are excited by the laser beam 1G and emit stimulated luminescence according to the image information accumulated and recorded at that point. At the same time, after the laser beam 1C is irradiated to the point 3a, a part of it is reflected there and scattered around. As shown in FIG. 2, which is an enlarged view of the vicinity of point 3a, a portion of the laser light scattered around by reflection is reflected on the incident end surface 4a of the condenser 4, as shown by arrows 11a, 11b, and 11C. Concentrating mirror 10
The light is reflected by the reflective surface of the sheet 3, and enters a portion of the sheet 3 other than the point 3a, and excites this portion to cause stimulated luminescence.

(Purpose of the Invention) In view of the above circumstances, the present invention provides a system in which excitation light that is irradiated onto a stimulable phosphor sheet and reflected at the irradiated portion is
It is an object of the present invention to provide a 7j radiation image information reading device in which a good reproduced image can be obtained by preventing radiation from being reflected there even if it is incident on a reflecting surface of a condensing mirror.

(Structure of the Invention) The radiographic image information reading "JAN" of the present invention is based on the above-mentioned conventional radiographic image information reading device.
In the vicinity of the Ajfm surface and the part of the sheet scanned by the excitation light, the stimulated luminescence emitted from this scanned part is reflected toward the incident end surface, but the excitation light reflected from the sheet is reflected. This feature is characterized in that a condensing mirror that does not have the same function as a conventional condensing mirror is placed in place of the conventional condensing mirror.

(Effects of the Invention) According to the present invention, the condensing mirror reflects only the stimulated luminescence light and does not reflect the excitation light, so that the stimulated luminescence light is emitted from areas other than those directly irradiated with the scanning excitation light. The image information read is more accurate.

(Example) Next, the present invention will be explained by examples.

In addition, in the embodiment described below, an example is shown in which the reflection of the excitation light is prevented not only at the condenser mirror but also at the incident end face of the condenser; This is because image information can be further improved by preventing the reflection of the excitation light, and in the present invention, it is not necessarily necessary to prevent the reflection of the excitation light at the incident end face of the light condenser.

In the embodiment of the radiation image information reading device of the present invention, which will be explained below, an excitation light antireflection film is provided on the incident end surface of the condenser, and the condenser mirror 10 does not allow stimulated luminescence light to pass through. It is exactly the same as the conventional reading device shown in FIG. 1, except that a condensing mirror is used that reflects but not the excitation light.

Therefore, since the operation of the apparatus itself has been explained with reference to FIG. 1, it will be omitted, and this embodiment will be explained with reference to FIG. 3, which corresponds to an enlarged sectional view taken along arrows 1 to 2 in FIG.

An excitation light anti-reflection film 13 is provided on the entrance end surface 4a of the condenser 4, the entrance end surface 4a of which is disposed along the scanning portion of the sheet 3 scanned by the excitation light 1b. The condensing mirror 10 is disposed such that the surface 10a faces the incident end surface 4a of the condenser 4.

The anti-fouling mirror 10 reflects the stimulated luminescence light incident on its reflective surface 10a, but must not reflect the excitation light due to transmission, absorption, or the like.

As a specific example of a condensing mirror 1o having such optical properties, the surface of metal aluminum is treated with colored alumite, and this treated part force (@colored aluminium 1~film) is applied to the irregular surface 10.
An example is a. In this case, the surface of metallic aluminum is anodized and at the same time colored with a dye that reflects stimulated luminescence light but absorbs excitation light, thereby giving the metallic aluminum surface the optical properties described above. A colored alumite film is formed as a reflective surface. Further, as another specific example of the condensing mirror 10, glass,
An example is one in which a dichroic coating is applied to the surface of a base made of plastic or the like, and this dichroic coating is used as a reflective surface 10a (that is, a dichroic mirror).

Of course, in this case, the dichroic coating provided on the surface of the substrate has optical properties such that it reflects stimulated luminescence light but transmits excitation light.

Excitation light having a relatively long wavelength (for example, wavelength 633 nm) that is incident on these mirrors 10 is either absorbed by the reflecting surface 10a (in the former example) or transmitted through the reflecting surface 10a (in the latter example); relatively short wavelength (e.g. wavelength 400 nm
) is reflected by the mirror 10.

The excitation light anti-reflection film 13 installed on the incident end surface 4a of the condenser 4 prevents the excitation light from fouling and also prevents the reflection of stimulated luminescence light, thereby preventing the stimulated luminescence light from entering the condenser 4. It needs to be something that can be efficiently introduced into the interior. A specific example of the excitation light antireflection film 13 having such optical properties is as follows.
An example of this is a vapor-deposited thin film of a material having a refractive index lower than that of the material of the light condenser 4. When such a vapor-deposited thin film is provided, if its optical thickness is set to 1/4 of the wavelength of the excitation light, the reflection of the excitation light will be minimized. When there is a relationship of nl-E1 between n2 and n2, there is no reflection of the excitation light at all. Specific examples of the material of the light condenser 4 include plastic, glass, etc., but M(JF2, C
aF2. Examples include cryolite. Note that such a vapor-deposited thin film prevents reflection of excitation light and also prevents reflection of stimulated luminescence light, so that stimulated luminescence light is efficiently introduced into the light collector 4. Reflection is prevented by a vapor-deposited thin film,
Behind the excitation light and stimulated luminescence light introduced into the light condenser, the excitation light is absorbed and removed by a filter provided between the condenser 4 and the 7th column 5, but the stimulated luminescence light is The light passes through this filter and is received by the photomultiplier 5.

Note that the condensing mirror 10 is not limited to the one described above, and may be any mirror that does not reflect excitation light but only reflects stimulated luminescence light.

As explained above, according to the present invention, the excitation light that is irradiated onto the sheet and reflected at the irradiated portion is prevented from entering the sheet again, so that the excitation light can be scanned to The stimulated luminescence light emitted 1q via the 1q corresponds accurately to the information apertures stored and recorded, and accurate image information can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a radiation image information reading device, and FIG. 2 is a point 3a3! in FIG. 7. FIG. 3 is an enlarged sectional view showing an embodiment of the present invention taken along the arrow n-'II in FIG. 1. FIG. 2... Galvanometer mirror 3... Sheet 4...
・Concentrator 4a...Incidence end face 5...7n Toma Az 10...Condensing mirror 2nd
Figure 3

Claims (1)

[Scope of Claims] A scanning optical system that scans excitation light on a stimulable phosphor sheet on which radiographic image information is stored and recorded, an incident end surface being provided near a portion of the sheet scanned by the excitation light, a light condenser that collects stimulated luminescence light emitted from the sheet by scanning the excitation light from the incident end face; disposed near the incident end face of the light condenser and the scanned portion of the sheet; The stimulated luminescence light emitted from this scanned part is reflected toward the incident end face, but the excitation light reflected by this scanned part is not reflected.It is focused by a condensing mirror and this condenser. The stimulated luminescent light is passed through a filter that selectively transmits the stimulated luminescent light.
A radiation image information reading device comprising a photoelectric converter that receives light and photoelectrically converts it into an electrical signal.