JPH065362B2 - Radiation image information reader - Google Patents

Description

The present invention relates to a radiation image information reading device for reading image information by exciting and scanning an image conversion panel storing and recording radiation image information.

[Background of the Invention]

For example, when a photostimulable phosphor is irradiated with radiation such as X-rays and ultraviolet rays, a part of the energy of this radiation is stored and recorded in the phosphor, and when the phosphor is subsequently irradiated with excitation light,
The phosphor emits stimulated light according to the accumulated energy.

The radiation image conversion panel is a panel having a stimulable phosphor layer having such characteristics (hereinafter, simply referred to as "panel" except for special cases), and the stimulable phosphor is a human body. It is possible to record a radiation image such as X-ray as a latent image, and if this latent image portion is irradiated with excitation light such as laser light,
Stimulated stimulated emission corresponding to the density of the latent image occurs. Therefore, if the stimulated emission light is detected by a photodetector such as a photomultiplier (photomultiplier tube) and appropriately processed, a recorded radiation image can be obtained.

After the radiation image was obtained, the panel was irradiated with erasing light such as halogen lamp light to erase the residual image remaining on the panel, so that the panel could be used repeatedly.

By the way, in such a conventional reading device, the distance between the reading unit that irradiates the panel with the excitation light to read the radiation image and the erasing unit that irradiates the erasing light to erase the afterimage is large. Therefore, there is a problem that the reading apparatus main body is very large, and there has been a demand for miniaturization of the apparatus.

Therefore, it is conceivable to bring the reading unit and the erasing unit close to each other, but in this case, the following problems occur.

In other words, due to the characteristics of the halogen lamp in the erasing section, afterglow occurs for a while even after the energization is stopped.Therefore, when the reading is resumed immediately, the photodetector in the reading section detects this afterglow. However, the image quality may be affected. Therefore, the reading of the radiation image could not be restarted until the afterglow decreased at least to the extent that the reading of the radiation image was not affected.

[Object of the Invention]

An object of the present invention is to provide a radiation image information reading apparatus that can achieve downsizing of the apparatus main body and shortening of the repeating cycle from recording to afterimage erasing.

[Structure of Invention]

In the radiation image information reading apparatus of the present invention to achieve the above object, the radiation image information of the subject is recorded by radiation imaging as a latent image, and the stimulable phosphor panel is scanned with excitation light to perform the accumulation recording. In the radiation image information reading device having excitation / reading means for photoelectrically reading the radiation image information, and erasing means for erasing the afterimage of the radiation image conversion panel after the reading of the radiation image information is completed, The reading unit and the erasing unit integrally move back and forth with respect to the radiation image conversion panel to read the radiation image information and erase the afterimage, and an optical path between the erasing unit and the radiation image conversion panel. A light-shielding means for opening and closing, and the light-shielding means opens the optical path only while the afterimage is being erased by the erasing means. It is characterized in.

〔Example〕

Examples of the present invention will be described below. FIG. 1 is a block diagram showing the configuration of an embodiment of the radiation image information recording / reading apparatus, and shows an example in the case of being applied to chest radiography.

The radiation generation source 1 is controlled by the radiation control device 2 and irradiates the subject (human chest or the like) M with radiation. The radiation image information recording / reading device 3 is provided with the above-mentioned panel 4 on the surface facing the radiation source 1 with the subject M sandwiched therebetween, and the panel 4 is the radiation transmittance of the subject M with respect to the radiation dose from the radiation source 1. By accumulating energy according to the distribution in the photostimulable phosphor layer, the subject M
To form a latent image of.

The light beam generator 5 generates a light beam whose emission intensity is controlled, and the light beam reaches a scanner 6 via various optical systems described later, is deflected there, and is further reflected by a reflecting mirror 7.
The optical path is changed by and is guided to the panel 4 as excitation scanning light.

The condensing body 8 has a condensing end formed of an optical fiber in the vicinity of the panel 4 scanned by the excitation light, and stimulated emission substantially in proportion to the latent image energy from the panel 4 scanned by the light beam. Receive light. Reference numeral 9 is a filter that passes only the light in the stimulated emission wavelength range from the light introduced from the light collector 8, and the light passing therethrough is incident on the photomultiplier 10 and converted into a current signal corresponding to the incident light. To be converted.

The output current from the photomultiplier 10 is the current / voltage converter 1
After being converted into a voltage signal by 1 and amplified by the amplifier 12,
It is converted into digital data by the A / D converter 13. Then, this digital data is sequentially stored in the image memory 14. Reference numeral 15 denotes a CPU, which performs various image processing (for example, gradation processing, frequency processing, movement, rotation, statistical processing, etc.) on the image information stored in the memory 14, and the image information as a processing result is , Is displayed on the image display device 16. Reference numeral 17 is an interface for transmitting the image information in the memory 14 to the outside or receiving similar information from the outside. Reference numeral 18 denotes a read gain adjusting circuit. With this circuit, the light beam intensity adjustment of the light beam generator 5, the photomal gain adjustment by adjusting the power source voltage of the high voltage power source 19 for photomul, the current / voltage converter 11 and the amplifier 12 are performed. And the input dynamic range of the A / D converter 13 are adjusted, and the read gain of the radiation image information is adjusted comprehensively.

FIG. 2 is a view showing a mechanical portion in which the panel 4 is fixedly arranged and the excitation / read / erase unit 30 is movably provided. Reference numeral 21 is a frame forming an outer frame of the main body of the device 3.

The excitation / read / erase unit 30 is entirely movable plate 3
It is configured in a fixed state. A female screw body (not shown) is fixed to the moving plate 31, and the female screw body is screwed onto a male screw rod 26 rotated by a motor 25 attached to the frame 21. 27 is a guide rod. Therefore,
By driving the motor 25, the moving plate 31 moves in the direction of the arrow Y.
It can be moved in or out of the direction.

The above-mentioned light beam generator 5 is mounted on this moving plate 31 (not shown in FIG. 2), and the beam from there is an optical system (not shown) such as a beam expander for shaping (expanding) the beam diameter. ) Is reflected by a scanner 6 such as a galvanometer mirror or a polygon mirror (a galvanometer mirror is shown in the figure) to become scanning light, which passes through a condenser lens 32 such as an fθ lens for focus adjustment and is reflected. The optical path is changed by the mirrors 71 to 73 to become the excitation light 81.

The panel 4 is fixed to the left of the moving range of the exciting / reading / erasing unit 30 in FIG. 2, and the exciting light 81 is scanned on the panel 4 as a scanning line 80.

Here, the excitation light optical path from the light beam generator 5 to the reflecting mirror 71 is on the same plane and is configured to be parallel to the panel 4. By doing so,
It is possible to easily perform the optical path adjustment work of the light beam which requires the assembly of the device and the positional accuracy, and further it is possible to make the device compact.

The photomultiplier 10 is fixed to the moving plate 31, and the condensing end face 8a of the condensing body 8 that transmits the stimulated emission light to the photomultiplier 10 is provided.
Are located in the vicinity of the scanning line 80 and are arranged parallel to the scanning line 80.

Now, in this device 3, in the main scanning in the X direction (direction perpendicular to the paper surface of the drawing of FIG. 2) on the panel 4, the beam emitted from the light beam generator 5 is swung by the scanner 6 (scanned). ), The focusing lens 32 focuses on the surface of the panel 4.

On the other hand, the sub-scanning in the Y direction is performed by moving the moving plate 31 in the Y direction, that is, the excitation / reading / erasing unit 30 itself, with the panel 4 fixed in this embodiment.

Therefore, the panel 4 can be two-dimensionally scanned with the excitation light 81, and when stimulated emission light corresponding to the density of the latent image is generated in the portion scanned with the excitation light 81, the emission is condensed. It is condensed by the body 8 and guided to the photomultiplier 10, where it is detected and becomes an electric signal. Then, by processing this electric signal in synchronization with the main scanning and the sub-scanning, the image recorded as a latent image on the panel 4 can be reproduced.

In the apparatus of this embodiment, since the excitation / reading / erasing unit 30 is integrally configured as described above, the positional deviation (misalignment) between the respective parts is reduced, and more stable image reading is possible. Become.

Further, since the panel 4 is fixed to the frame 21 as described above, the possibility of damaging the panel 4 can be minimized, and the space required for moving the panel 4 is not necessary. Furthermore, the sub-scanning in the Y direction is
The reading / erasing unit 30 itself moves, and the moving range of the panel 4 in the Y direction is sufficient. Therefore,
The entire device can be downsized.

Further, since the space required for moving the panel itself is not required and the panel driving member is not required, the distance between the panel 4 and the subject can be significantly reduced, and scattered rays generated from the subject and the like can be significantly reduced. Therefore, it is possible to prevent the deterioration of the image information quality.

FIG. 3 shows details of the panel fixing portion. The panel 4 is integrated with the panel fixing plate 22 with an adhesive or the like, and a part of the exterior 23 attached to the frame 21 including a radiation irradiating portion is cut out, and the panel fixing plate 2 including the panel 4 is cut out.
2 is detachably installed and constitutes a part of the exterior 23. Reference numeral 24 is a mounting plate for the panel fixing plate 22. By integrally mounting the panel 4 on the frame 21 as described above, the distance between the panel 4 and the subject can be greatly reduced.

Note that if the parallelism between the panel 4 and the excitation / reading / erasing unit 30 changes, the reading accuracy will deteriorate, so the panel fixing plate 22 should be made of a material that is rigid and has good flatness. is important. In addition, the panel fixing plate 22
Also needs to choose the one that absorbs as little radiation as possible.

As the material of the panel fixing plate 22, various polymer materials, glass, metal and the like can be used, as described in detail later, but a rigid carbon material is preferable from the viewpoint of a small radiation absorption amount. The panel 4 is composed of a support 4a, a fluorescent layer 4b, and a protective layer 4c.
It is even more preferable if 2 is configured so as to also serve as the support 4a.

In this embodiment, the moving body is the excitation / read / erase unit 30.
Since the moving plate 31 is mounted with, the rapid speed change is not preferable, and it is necessary to adjust the speed within a range that does not affect reading when starting and stopping the sub-scan. FIG. 4 shows changes in the sub-scanning speed during the series of operations. If the speed changes rapidly as shown in (a), the optical system may be impacted, but as shown in (b). If you adjust the speed when starting and stopping the movement, it is difficult to give a shock. Further, it is more preferable to adjust so that the speed change becomes slow as in (c).
If a shock absorbing structure is adopted at both ends of the stroke of the moving plate 31 in addition to the speed change as shown in (b) or (c), the excitation / reading / erasing unit 30 mounted on the moving plate 31 can be operated. The impact relaxation of is more preferable.

Further, although the optical path is bent by the reflecting mirrors 71 to 73 in the above-described embodiment, this makes it possible to change the substantial optical path length between the scanner 6 and the scanning line 80 on the panel 4,
Since the space occupied by the fan-shaped scanning light can be reduced, inserting a plurality of such reflecting mirrors in the optical path greatly contributes to downsizing of the apparatus.

Further, in FIG. 2, the excitation light 81 is incident on the panel 4 obliquely from below. If the excitation light is incident on the panel 4 from the vertical direction, the excitation light may directly return to the light beam generation unit 5 due to reflection on the surface of the panel 4, which may lead to fluctuations in the light beam power.

In the mechanism for moving the excitation / read / erase unit 30,
It is preferable to use a laser light source, especially a semiconductor laser as the light beam generator 5 in terms of compactness, light weight, and low cost, but when reflected light enters the active region of the semiconductor laser, the laser oscillation mode changes, The light beam power fluctuates greatly and adversely affects image reading.
Therefore, in the present embodiment, as described above, the excitation light 81 is incident on the panel 4 from an oblique direction.

Further, in this embodiment, the incident end face of the light collector 8 is arranged substantially parallel to the panel 4 in FIG. With such a configuration, the efficiency of collecting stimulated emission light generated on the panel 4 is maximized, and read image information with a high S / N ratio can be obtained.

By the way, in order to enable repeated use without removing the panel 4 from the frame 21 as described with reference to FIG. 3, it is necessary to erase the latent image remaining after the reading. This erasing can be performed by irradiating the panel 4 with strong light. Therefore, as shown in FIG. 2, an erasing lamp 33 is provided substantially parallel to the light collector 8 and the lamp 33 is attached to the moving plate 31. Just fix it. Further, this lamp 33 is covered with a reflector 34 in order to efficiently irradiate the panel 4 with light from the lamp 33, and a shutter 35 is provided between the lamp 33 and the panel 4 so as to face the panel 4 only when necessary. Is intervening.

As for the mounting position of the erasing lamp 33, if it is close to the panel 4, it consumes less power and the lamp 33 itself can be made smaller and lighter. Further, as shown in FIG. 2, by passing the excitation light 81 between the condenser 8 and the erasing lamp 33, the dead space is reduced, and the device 3 itself can be made significantly compact. The erase lamp 33 used here is a halogen lamp.

Since the light collector 8 and the erasing lamp 33 are integrated in the unit 30, it is possible to sequentially erase the read-completed portion while the image is being read. When the light enters the optical body 8 or irradiates the scanning line 80 which is currently being read, a large noise occurs, which causes a problem of being detected by the photomultiplier 10.

Therefore, in order to prevent this, it is preferable to adopt a process in which reading is performed at the time of sub-scanning in the direction of arrow Y and erasing is performed at the time of returning to the opposite direction.

Further, in order to prevent the photocathode of the photomultiplier 10 from being deteriorated by the light at the time of erasing by the lamp 33, the light blocking means 36 is provided in the optical path from the scanning line 80 to the photomultiplier 10.
It is preferable to provide (FIG. 2). By doing so, the lamp light to the photomultiplier 10 can be blocked, the life of the lamp can be extended, and the obstacle for the next reading can be reduced.

In this case, the light blocking plate used as the light blocking means 36 may be replaced with a filter that transmits the stimulated emission light and attenuates the excitation light. A liquid crystal shutter can also be used as the light shielding means 36. Further, it is preferable that the light shielding unit 36 shields not only the erasing lamp light but also the radiation at the time of photographing. In this case, it is preferable to add a lead plate or the like as a material.

FIG. 5 is a diagram showing the operation timing of each part in image recording and reading. When the apparatus 3 is stopped, the unit 30 is in the lowest position, and when the activation switch is turned on, the unit 30 moves to the upper radiation irradiation standby position. During this movement, the erasing lamp 33 is turned on and the shutter 35 is opened to erase the latent image such as noise remaining on the panel 4, thereby preventing the fog of the old and new images. next,
When the unit 30 is in this standby position and the imaging (radiation irradiation) switch is turned on, radiation irradiation is performed,
A radiation image is recorded on the panel 4 according to the amount of radiation that has passed through the subject M. Then, after a lapse of a certain time, the reading operation is started by moving the excitation / read / erase unit 30. The certain period of time means a period of time until the momentary light emission and the momentary afterglow of the panel 4 due to the irradiation of radiation are sufficiently attenuated, and the energy recorded and accumulated in the panel 4 is not largely spontaneously released. Specifically, it is about 0.01 to 60 seconds, preferably 0.01 to 10 seconds.

In reading, after the moving speed of the moving plate 31 is stabilized, the light beam generator 5 and the scanner 6 are turned on for a predetermined time to be active, and the light shielding means 36 is opened so as to transmit light for a predetermined time. Therefore, after turning on the main switch, it is possible to detect the photomultiplier 10 which is always kept in the ON state. Reading is performed during this predetermined time. In this way, if each part except the photomultiplier 10 is operated only for the required time, it is effective for prolonging the life. In addition, by holding the photomultiplier 10 in the ON state until the main switch is turned off after the main switch is turned on, it takes several seconds to several tens of seconds until the sensitivity is stabilized after turning on. Even with the photomultiplier, it is possible to always detect with stable sensitivity. However, when a photomultiplier whose sensitivity is stabilized immediately after being turned on is used, it can be turned on for a predetermined time as in the case of the beam generator 5 and the scanner 6. After the reading is completed, when the moving plate 31 returns in the direction opposite to the arrow Y direction, the erasing lamp 33 is turned on, the shutter 35 is opened, and the latent image remaining on the panel 4 is the same as above. Will be erased.

By the way, it is possible to use the unit 30 instead of the radiation detector by moving the unit 30 to a prescribed place in the irradiation field at the time of irradiation with the structure in which the unit 30 is moved as described above. There is no need to newly provide a radiation detector, and there is no need to perform pre-reading prior to the original reading.

That is, the photodetector such as the photomultiplier 10 in the excitation / reading unit 30 can also be used as the radiation detector as a radiation detector, and the radiation generated at the time of irradiation of radiation, instantaneous light emission, instantaneous afterglow, etc. are utilized. When the radiation dose reaches the specified dose, a signal to stop the radiation irradiation is generated to prevent the radiation dose from fluctuating on the panel 4 and stabilize the image recording condition. It is possible to accurately detect and measure the amount and adjust the reading gain of stimulated emission.

Further, on the moving excitation / reading unit 30, the current / voltage converter 11, the amplifier 12, and the A / A converter shown in FIG.
It is preferable to mount the D converter 13 from the viewpoint that it can be output from a digital signal instead of an analog signal that is easily affected by noise.

Further, in the above-described embodiment, the recording / reading apparatus for standing is shown in which the panel 4 is vertically arranged vertically. However, the same configuration can be realized for so-called "decubitus" in which the panel 4 is laid horizontally. Of course, a C-arm (X-ray source-reader integrated) or a vehicle-mounted type can also be used.

Examples of the photostimulable phosphor used in the panel 4 of the present invention include:
Use an alkali halide phosphor. The phosphor is represented by the following general formula ^{M I X · aM II X '} 2 · bM III X "3: cA ( where, M ^I is Li, Na, K, at least one alkali metal selected from Rb and Cs Yes, M ^II is B
e, Mg, Ca, Sr, Ba, Zn, Cd, Cu and N
It is at least one divalent metal selected from i. M
^III is Sc, Y, La, Ce, Pr, Nd, Pm, S
m, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y
It is at least one trivalent metal selected from b, Lu, A, Ga and In. X, X'and X "are F, C
, At least one halogen selected from Br and I. A is Eu, Tb, Ce, Tm, Dy, Pr, H
o, Nd, Yb, Er, Gd, Lu, Sm, Y, T,
It is at least one metal selected from Na, Ag, Cu and Mg.

A is a numerical value in the range of 0 ≦ a ≦ 0.5, and b is 0 ≦ a ≦ 0.5.
b is a numerical value in the range of 0.5, and c is a numerical value in the range of 0 <c <0.2. ) Alkali halide phosphors represented by. The alkali halide phosphor may have a stimulable phosphor layer formed by a method such as vapor deposition or sputtering.

The above alkali halide phosphor does not have to be used alone, and may be used as a mixture with another stimulable phosphor. However, when such a mixture is used, the mixing ratio of the alkali halide phosphor is 50 wt% or more, and further 70 wt%.
% Or more is preferable.

This alkali halide phosphor has a wavelength of 500 to 9 as shown by the stimulated excitation spectrum and stimulated emission spectrum shown by the solid line in FIG.
It excites light with a wavelength of 250 to 500 nm by excitation light with a wavelength of 00 nm. Its emission sensitivity is better than that of the fluorescent material (dashed line) used in conventional devices, and the oscillation wavelength range of the semiconductor laser light source. Matching with is preferable.

Further, as shown in FIG. 7, when the excitation light was excited for the time (10 μsec) indicated by the broken line, the fluorescent substance used in the device of the present invention showed a sharp rise and fall curve (a) as shown by the solid line. There is a slope. This shows that the response characteristic of stimulated emission is better than that of the curve (b) of the phosphor used in the conventional device shown by the one-dot chain line and the curve (c) shown by the two-dot chain line, and (a) is (b ), It is possible to read at a speed more than double. Further, from this figure, it can be seen that the phosphor used in the device of the present invention has almost no photostimulated afterglow and has a short life as compared with the phosphor used in the conventional device. The image quality does not deteriorate. In the conventional device (panel transfer type), the panel had to be moved from the recording location to the reading location, which required moving time. However, in the present invention, the panel is fixed, so the moving time is also reduced. Since it is not necessary, and since the alkali halide phosphor has a short instantaneous light emission afterglow at the time of radiation irradiation and recording, and has a short life, it is not necessary to delay the reading start until the instantaneous light emission afterglow disappears, so recording (shooting) The reading can be started almost at the same time, and thus it is possible to observe the image quickly.

In the radiation conversion panel of the present invention, a support for supporting the stimulable phosphor layer is provided when the stimulable phosphor layer has no self-supporting ability. As the support, various polymer materials, glass, metals, etc. are used as described above, and plastic films such as cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, and polycarbonate film. A metal sheet such as an aluminum sheet, an iron sheet, a copper sheet, or a metal sheet having a coating layer of the metal oxide is preferable.

The surface of these supports may be a smooth surface or a matte surface for the purpose of improving the adhesiveness to the photostimulable phosphor layer. Further, these supports may be provided with an undercoat layer on the surface on which the stimulable phosphor layer is provided for the same purpose. The layer thickness of these supports varies depending on the material of the support used and the like, but is generally 50 to 2,000 μm, and more preferably 80 to 1,000 μ from the viewpoint of handling.

In the radiation image conversion panel of the present invention, generally, on the surface opposite to the surface on which the support of the stimulable phosphor layer is provided,
A protective layer for physically or chemically protecting the photostimulable phosphor layer may be provided. This protective layer may be formed by directly coating the protective layer coating liquid on the stimulable phosphor layer, or by separately forming a protective layer previously formed on the stimulable phosphor layer. Is also good. Alternatively, a procedure of forming a stimulable phosphor layer on a separately formed protective layer may be adopted. Materials for the protective layer include cellulose acetate, nitrocellulose, polymethylmethacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyester, polyethylene terephthalate, polyethylene, polyvinylidene chloride, nylon, polytetrafluoroethylene, polytrifluoride-chloride. Ethylene, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene chloride-vinyl chloride copolymer,
A usual protective layer material such as vinylidene chloride-acrylonitrile copolymer is used. Further, this protective layer is made of SiC, SiO ₂ , Si by a vapor deposition method, a sputtering method or the like.
N, may be formed by stacking an inorganic material such as A ₂ O _3.
Generally, the thickness of these protective layers is preferably about 0.1 to 100 μm.

〔The invention's effect〕

According to the present invention, even when the reading unit and the erasing unit are integrally provided and unitized, a high-quality radiation image can be obtained without being affected by the afterglow of the erasing lamp.
Therefore, even if the apparatus main body is downsized, it is possible to shorten the time from the afterimage erasure to the reading restart without degrading the image quality.

[Brief description of drawings]

FIG. 1 is a block diagram of the configuration of a radiation image information recording / reading apparatus according to an embodiment of the present invention, FIG. 2 is a side view showing an internal mechanism of the apparatus, and FIG. 3 is a side view showing a panel mounting structure, FIG. 4 is a movement characteristic diagram of the excitation / read / erase unit, FIG. 5 is a time chart showing the operation timing of the apparatus, FIG. 6 is a spectrum characteristic diagram of the stimulable phosphor, and FIG. It is a response characteristic figure of a fluorescent substance. 1 ... Radiation generation source, 2 ... Radiation control device, 3 ... Radiation image information recording / reading device, 4 ... Radiation image conversion panel, 5 ...
Light beam generator, 6 ... Scanner, 7 ... Reflector, 8 ... Condenser, 9 ... Filter, 10 ... Photomul, 11 ... Current / voltage converter, 12 ... Amplifier, 13 ... A / D converter, 14 ...
Image memory, 15 ... CPU, 16 ... Display, 17 ... Interface, 18 ... Gain adjusting circuit, 19 ... High-voltage power supply, 21 ... Frame, 22 ... Panel fixing plate, 23 ... Panel fixing plate mounting plate, 24 ... Exterior , 25 ... Motor, 26
... Male threaded rod, 27 ... Guide rod, 28 ... Frame, 30 ... Excitation
Reading / erasing unit, 31 ... Moving plate, 32 ... Condensing lens, 33 ... Erase lamp, 34 ... Reflecting plate, 35 ... Shutter, 36 ... Shading means, 71-73 ... Reflecting mirror, 80 ... Scanning line, 81 ... Excitation light.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mikio Takeuchi 1 Sakura-cho, Hino City, Tokyo Photo Konishi Roku Photo Industry Co., Ltd. (72) Inventor Mitsuru Ishii 1 Sakura-cho, Hino City Tokyo, Photo Roku Konishi Photo Industry Co., Ltd. (56) Reference JP-A-58-200269 (JP, A)

Claims (2)

[Claims] 1. A photostimulable phosphor panel, on which radiation image information of a subject is stored and recorded as a latent image by radiography, is scanned with excitation light to photoelectrically read the stored and recorded radiation image information. In a radiation image information reading apparatus having an excitation / reading means and an erasing means for erasing an afterimage of the radiation image conversion panel after the reading of the radiation image information is completed, the excitation / reading means and the erasing means are integrated. A reciprocating movement relative to the radiation image conversion panel to read the radiation image information and erase an afterimage, and a light shielding means for opening and closing an optical path between the erasing means and the radiation image conversion panel, The radiation image information reading device is characterized in that the light path is opened by the light shielding means only while the afterimage is erased by the erasing means. . 2. A radiation image information reading apparatus according to claim 1, wherein a halogen lamp is used as said erasing means.