JPH0271662A - Radiograph information reader - Google Patents

Abstract

PURPOSE:To correct a sensitivity change due to a fluctuation in a light intensity versus photoelectric current characteristic of a photodetector by irradiating it with a reference light of the same wavelength area as that of a luminescent light to regulate the gain of a read system. CONSTITUTION:A stimulable phosphor sheet 1 with radiograph information of an object stored thereupon is carried in a direction of the arrow B and a stimulating light 3 emitted from a laser light source 2 scans the sheet 1 in a direction of the arrow A nearly at a right angle in the direction of the arrow B. The stimulated phosphor light 7 emitted from the part on the sheet 1 irradiated with the stimulating light 3 is led to a photomultiplier 9 via an optical guide 8 and an electric signal S representing the stimulated phosphor light quantity is inputted to a read circuit 20. A CPU 27 lights a tungsten lamp 25, which is a reference light of the same wavelength region as that of the stimulated phosphor light 7. A high voltage power supply Hv is adjusted to obtain a prescribed readout output in response to a signal S4 representing the reference light intensity from a light source intensity detection circuit 29, thereby the gain of the read system is adjusted.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention aims to irradiate excitation light onto a stimulable phosphor sheet that stores and records radiographic image information, and to generate stimulable fluorescent light irradiated with the excitation light. Regarding a radiation image information reading device that photoelectrically detects stimulated luminescence light generated from a portion of a body sheet and reads radiation image information, in particular, the sensitivity of a photodetector that detects the stimulated luminescence light is corrected. The present invention relates to a radiographic image information reading device with functions.

(Prior art) When a certain type 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 accumulated in the phosphor, and this It is known that when a phosphor is irradiated with excitation light such as visible light, the phosphor exhibits stimulated luminescence depending on the accumulated energy. stimulable phosphor).

Using this stimulable phosphor, radiation image information of the human body, etc. is temporarily recorded on a stimulable phosphor sheet, and this stimulable phosphor sheet is scanned with excitation light such as a laser beam to generate stimulated luminescence light. The resulting stimulated luminescent light is read photoelectrically to obtain an image signal, and based on this image signal, a radiation image is output as a visible image to a recording material such as a photographic light-sensitive material or a display device such as a CRT. An image information recording and reproducing system has already been proposed by the present applicant (Japanese Patent Application Laid-Open No. 1249/1989).
No. 2, No. 5B-11395, etc.).

In addition, the present applicant has developed a microscopic vL that uses the above-mentioned stimulable phosphor sheet to record and reproduce electron microscopic images with high sensitivity and high image quality, and to facilitate various processing.
We proposed a new electron microscope image recording and reproducing system in which electric signals carrying images can be directly obtained (Japanese Patent Application Laid-open No. 81-517
No. 38, JP-A No. 61-93539, etc.). An electron microscope image recording and reproducing system using this stimulable phosphor sheet basically stores and records the electron beam that has passed through the sample on the sheet in a vacuum state, and then irradiates the sheet with excitation light to record the stored energy. is emitted as light, this emitted light is detected photoelectrically to obtain an image signal, and this image signal is used to reproduce the transmitted electron beam image of the sample.

In the radiation image information reading device that reads the above-mentioned radiation image or electron microscope image (herein collectively referred to as radiation image) information, a photodetector for detecting stimulated luminescence light has conventionally been a photoelectron multiplier. tubes (photomultipliers) are widely used.

However, this photomultiplier tube has a problem in that the light intensity and photocurrent characteristics vary depending on the temperature. This characteristic also changes over time. If this characteristic changes,
The value of the image signal obtained by reading the radiation image information varies overall. Such problems are not limited to photomultiplier tubes, but are particularly noticeable in photodetectors equipped with a pie-alkali photocathode or a multi-alkali photocathode.

The fluctuation of the above-mentioned light intensity emitted photocurrent characteristics can be explained by, for example,
As shown in No. 11347 and No. 57-1958,
A means for extracting all or part of the excitation light, a means for transmitting the extracted excitation light to a photodetector, and a comparison between the output signal of the photodetector and a reference voltage to adjust the gain of the reading system. It becomes possible to compensate by providing means.

(Problem to be Solved by the Invention) However, the manner in which the light intensity/emission photocurrent characteristics change due to temperature changes depending on the wavelength of the light received by the photodetector, and the wavelengths of the excitation light and stimulated emission light, for example, 833 each
nm, 390 nm, etc., which are significantly different from each other.
Even if the excitation light is received by a photodetector and its sensitivity is corrected as described above, it is not possible to precisely correct the sensitivity when this photodetector actually detects stimulated luminescence light. .

Even if the sensitivity correction described above is not performed strictly, for example, when reading and reproducing radiation image information of the human body,
Since the density of the reproduced image shifted only slightly, there was no particular problem in practical use.

However, in the above-mentioned electron microscope image recording and reproducing system, it is desired to perform reading with higher precision than when recording and reproducing radiation image information of the human body, and in this case, the accuracy of the sensitivity correction described above is low. This may cause problems in practice. Furthermore, quantitative measurement of the radiation dose accumulated in a stimulable phosphor sheet based on the read image signal has been conventionally carried out, but in this case, the sensitivity correction described above must be strictly performed. , errors occur in the measured values of radiation dose.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a radiation image information reading device that can extremely accurately correct sensitivity changes due to variations in light intensity and photocurrent characteristics of a photodetector. That is.

(Means and Effects for Solving the Problems) The radiation image information reading device of the present invention irradiates the stimulable phosphor sheet with excitation light as described above, and uses the stimulated luminescence light generated by the excitation light to pass through a photomultiplier. In a radiation image information reading device that performs photoelectric detection using a reading system including a photodetector such as and means for adjusting the gain of the reading system so that when the photocathode is irradiated with the reference light, a predetermined output corresponding to the reference light intensity is obtained from the reading system. It is something.

As mentioned above, if the sensitivity is corrected by making the photodetector receive the reference light in the same wavelength range as the stimulated emission light, this correction will be in accordance with the light intensity and photocurrent characteristics of the photodetector for the stimulated emission light. becomes.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 shows a radiation image information reading device according to a first embodiment of the present invention. In this radiation image information reading device, the stimulable phosphor sheet 1 on which the radiation image information of the subject has been accumulated and recorded is moved by a sub-scanning means such as an endless belt 13 driven by an appropriate method (not shown) as indicated by the arrow B.
conveyed in the direction. On the other hand, a light beam (excitation light) 3 emitted from a laser light source 2 is reflected and deflected by a light deflector such as a rotating polygon mirror 4 that rotates at a predetermined angular velocity, passes through a condensing lens 5 such as an fθ lens, and is mirrored. 6, the sheet 1 is main-scanned in the direction of arrow A, which is substantially perpendicular to the direction of arrow B (sub-scanning direction). From the location on the sheet 1 irradiated with this excitation light 3, stimulated luminescence light 7 is emitted in an amount corresponding to the radiographic image information stored and recorded.
This stimulated luminescent light 7 is guided through a light guide 8 to a photomultiplier 9 as a photodetector, and is photoelectrically detected. The light guide 8 is made by molding a light-guiding material such as an acrylic plate, and is arranged so that the linear entrance end surface 8a extends along the main scanning line on the stimulable phosphor sheet 1. The output end face 8b formed in an annular shape is coupled to the light receiving surface of the photomultiplier tube 9 via an optical filter lO that selectively transmits the stimulated luminescent light 7.

The stimulated luminescence light 7 entering the light guide 8 from the input end face 8a travels through the interior of the light guide 8 through repeated total reflection, exits from the output end face 8b, is received by the photomultiplier tube 9, and is then received by the photomultiplier tube 9. The amount of stimulated luminescence light 7 carrying radiation image information is detected by this photomultiplier tube 9 . The electrical signal S indicating the amount of stimulated luminescence thus detected is sent to the reading circuit 20.
and undergoes processing such as logarithmic conversion and amplification.

The output signal S' of this reading circuit 20 is sent to the A/D converter 22.
Digitized by. This digitized image signal Sd is input to an image reproducing device 23 such as a CRT or an optical scanning recording device, and is used to reproduce the radiation image recorded on the stimulable phosphor sheet 1. Note that the image signal Sd may be stored in a storage medium such as an optical disc.

Next, a description will be given of the point of correcting the above-mentioned fluctuation in the light intensity and photocurrent characteristics of the photomultiplier tube 9. endless belt 1
3 is made of a transparent material, and there is a light guide 8 inside it.
A tungsten lamp 25 is disposed so as to face the incident end surface 8a of the tungsten lamp 25.

This tungsten lamp 25 is turned on by being supplied with current from the stabilized power source 2B. The drive of this stable pillow type [28]
It is controlled by CPU27. Also, when placed close to the tungsten lamp 25, out of the light emitted by the lamp 25,
In order to detect the intensity of only the light in the same wavelength range as the stimulated luminescence light, a photodiode 28 is provided with an optical filter 44 that selectively transmits light in the wavelength range, and the output of the photodiode 28 is S1 is input to the light source light intensity detection circuit 29. - The operation of the high-voltage power supply 30 that applies the high-voltage voltage Hv to the electron multiplier tube 9 is also controlled by the above-mentioned CP.
Controlled by U27. Further, a temperature sensor 31 is provided near the photocathode of the photomultiplier tube 9, and an output S2 of this temperature sensor 31 is input to the CPU 27.

The configuration related to sensitivity correction of the photomultiplier tube 9 is extracted and shown in FIG.

When the temperature detected by the temperature sensor 31 changes by more than a set value, the CPU 27 sends a lighting signal S3 to the stabilized power supply 2B.
to turn on the tungsten lamp 25. Note that if the radiation image information is being read from the stimulable phosphor sheet 1 at the time when the temperature changes by more than the set value, the CPU 27 outputs the lighting signal S3 after this reading is completed.
Output. In this example, the wavelength of the excitation light 3 is 833
Furthermore, when the stimulable phosphor sheet 1 is irradiated with the excitation light 3, stimulated luminescence light 7 with a wavelength of 390 nm is emitted. emanate. This group - single light 3
2 passes through a transparent endless belt 13 and is connected to a light guide 8.
The light travels through the interior and is received by the photomultiplier tube 9.

At this time, only the reference light 32 having a wavelength of around 390 nm is received by the photomultiplier tube 9 due to the effect of the optical filter IO described above. In this way, when the photomultiplier tube 9 receives the reference light 32, the digital signal Sd output from the A/D converter 22 indicates the light intensity of the reference light 32 received by the photomultiplier tube 9. The signal Sd is input to the CPU 27. In addition, the reference light 3 emitted by the tungsten lamp 25
2 is also received by the photodiode 28, and a light source light intensity detection circuit 29 receives the output S2 of the photodiode 28.
A signal S4 indicating the light intensity of the reference light 32 is output from the reference light 32.

The tungsten lamp 25, which is turned on by the stabilized power supply circuit 2B, emits a reference light 32 of approximately constant intensity, but the light intensity of the reference light 32 may vary slightly due to disturbances or the like. This light intensity is detected by the photodiode 28, which has an extremely small change in sensitivity, with an error that is sufficiently lower than the output error level of the photomultiplier tube 9, which is to be corrected as described later. In other words, the above-mentioned signal S4 indicates the light intensity of the reference light 32 with sufficiently higher accuracy than the above-mentioned error level.

The CPU 27 compares this signal S4 with the output signal Sd of the A/D converter 22, and generates a correction signal S based on the comparison result.
5 is sent to the high-voltage power supply 30, and the reading sensitivity of the photomultiplier tube 9 is changed by changing the value of the high-voltage voltage Hv, so that a signal Sd of a predetermined value is obtained for a predetermined value of the signal S4. To control the high voltage Hv in this way, for example, a signal S
4 and the signal Sd is stored in the memory in the form of a table, and if the value of the signal Sd is smaller (larger) than the appropriate value that satisfies this relationship, the high voltage Hv is gradually increased (decreased). ) may be output from the CPU 27, and the output of the correction signal S5 may be stopped when the signal Sd reaches the appropriate value.

When the above operations are completed, the CPU 27 turns off the tungsten lamp 25, and a state is reached in which normal radiation image information reading can be performed. As described above, by setting the high voltage Hv so that a signal Sd of a predetermined value is obtained for a predetermined value of the signal S4, the light intensity emission photocurrent characteristics of the photomultiplier tube 9 can be varied. Even if the radiation image information is read from the next time, a read image signal Sd of a predetermined value will always be obtained for the stimulated luminescence light 7 of a certain intensity.

Next, a second embodiment of the present invention will be described with reference to FIG. Note that in FIG. 3, elements equivalent to those in FIG. 2 are given the same numbers, and explanations thereof will be omitted unless particularly necessary (the same applies hereinafter). In the apparatus shown in FIG. 3, the tungsten lamp 25 is housed in a case 40, and a shutter 41 is attached to the opening of the case 40. tungsten lamp 25
continues to light while the radiation image information reading device is powered on, and the CPU 27 controls the opening and closing of this shutter 41 to control the state in which the reference light 82 is irradiated onto the photomultiplier tube 9 and the state in which the reference light 82 is irradiated onto the photomultiplier tube 9. 32 is shut off and normal radiation image information reading is performed.

Further, in this embodiment, the tungsten lamp 25 is driven by the light amount stabilizing circuit 42 so that the intensity fluctuation of the reference light 32 is made sufficiently smaller than the output error level of the photomultiplier tube 9 to be corrected.

Then, the CPU 27 generates a signal S to be obtained when the reference light 32, which is essentially constant in intensity as described above, is irradiated with the reference light 32.
It stores the value of d, and if there is a deviation between the signal Sd actually input from the A/D converter 22 and the above-mentioned stored value, it outputs a correction signal S5 according to this deviation. The high voltage Hv is changed and the sensitivity of the photomultiplier tube 9 is set so that the above deviation is eliminated.

The device of the second embodiment explained above is the first embodiment shown in FIG.
It has the advantage that the configuration is simplified compared to the device of the embodiment. On the other hand, the device of the first embodiment has the advantage that since fluctuations in the emission intensity of the tungsten lamp 25 are allowed to some extent, it is possible to use the stabilized power source 2B, which is simpler than the light amount stabilizing circuit 42, for driving the power source. have

Next, a third embodiment of the present invention will be described with reference to FIG. Compared to the device shown in FIG. 3, the device shown in FIG.
The difference is that a reference light source consisting of a sealed β-ray source 45 and a scintillator 46 is used instead of the tungsten lamp 25.

The scintillator 4B receives the β rays emitted from the β ray source 45 and emits reference light 32 having the same wavelength as the stimulated luminescent light. In this apparatus, the sensitivity correction of the photomultiplier tube 9 is performed in the same manner as in the apparatus of the second embodiment.

+4(:, etc.) can be used as the above-mentioned β-ray source. For example, the half-life of 14c is 5730 years, so the above-mentioned light source has less deterioration over time and less characteristic fluctuation due to temperature changes. Moreover, it has the advantage of not requiring a power source.

As a light source having the same advantages as the above-mentioned light source, a light source in which scintillator particles 48 are dispersed in a polymer 47 containing 14C and sealed with a container 49 can be used, as shown in FIG. You can also do it.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. 6 to 8. First, FIG. 6 shows the sheet holding means and sub-scanning means of the radiation image information reading apparatus of the fourth embodiment. The platen 51 as a sheet holding means has an inwardly convex cylindrical surface 51a, and this cylindrical surface 51
A drive roller 56 and a roller 57 driven by the drive roller 56 are provided close to the lower end of the roller a. The stimulable phosphor sheet 1 on which radiation image information has been stored and recorded is conveyed by a known sheet conveying means (not shown), and its front end is fed to the lower part of the platen 51. Then, the roller 56 rotates and feeds the sheet 1 along the cylindrical surface 51a to a predetermined position. In this way, the stimulable phosphor sheet 1 is held on the platen 51 as shown by the dashed line in FIG. The platen 51 has a screw rod 5 at its lower part.
When the screw rod 53 is rotated by the motor 54, the two guide rails 55 move from the position shown by the solid line in FIG. It is possible to move in the direction of arrow G along at a constant speed. In this apparatus, the screw rod 53, motor 54, and guide rail 55 constitute a sub-scanning means.

Above the platen 51, a scanning optical system 58 as shown in FIGS. is read.

In the scanning optical system 58, the excitation light source is He.
-Ne laser 59 emits laser light 60 as excitation light. This excitation light 60 passes through a filter 61 that cuts unnecessary wavelength light, passes through an acousto-optic modulator (AOM) 82 for adjusting the intensity, and then enters two reflection mirrors 63 and 64. to change the optical path.

The excitation light 60 reflected by the mirror 64 passes through a beam expander 66 and is expanded to a predetermined beam diameter, and then the light in the wavelength range is transmitted, and the light in the wavelength range of stimulated luminescence light is reflected. The light is incident on the dichroic mirror B7.

The excitation light 60 that has passed through the dichroic mirror 67 is incident on a spinner 71 disposed on its optical path and is reflected and deflected. This spinner 71 continuously rotates a deflection mirror 72, which is provided with a reflecting surface 72a with an inclination of 45'' with respect to the incident excitation light 60, at high speed in the direction of arrow H by a spindle motor 2A. , this deflection mirror 72 is arranged so as to reflect the excitation light 60 on the central axis of the cylindrical surface 51a of the platen 51, and the optical path length of the laser beam from this reflection position to the top of the stimulable phosphor sheet 1 is always constant. In addition, in the optical path of the excitation light 60 reflected and deflected by the mirror 72, there is a condenser lens 73 that focuses the excitation light 60 incident as parallel light onto a desired spot on the stimulable phosphor sheet 1. It is provided.

This condensing lens 73 is a part of the spinner 71,
It is rotated at high speed integrally with the deflection mirror 72. The excitation light 60 reflected and deflected by the spinner 71 repeatedly travels on the stimulable phosphor sheet 1 in the direction of arrow H (see FIG. 7).
main scan. At the same time, as mentioned above, the platen 5
1 moves in the direction of arrow G at a constant speed, sub-scanning is performed, and the excitation light 60 scans the stimulable phosphor sheet 1 two-dimensionally.

Note that the condensing lens 73 as described above can be placed close to the stimulable phosphor sheet 1 without increasing its diameter, so a lens with a short focal length can be used as the condensing lens 73. The excitation light can be focused to an extremely small spot diameter and high-density reading can be performed.

The portion of the stimulable phosphor sheet 1 irradiated with the excitation light BO emits stimulated luminescence light 74 corresponding to the image information stored and recorded in that portion. This stimulated luminescence light 74 is emitted as non-directional light from the excitation light irradiation position, but a condenser lens 73 is arranged at a distance of focal length f from the excitation light irradiation position.
It becomes parallel light by passing through it. The stimulated luminescence light 74 that has become parallel light is reflected by the deflection mirror 72 of the spinner, and then enters the dichroic mirror 67 and is reflected. A detection lens 75 that focuses the stimulated luminescence light 74 is provided on the optical path of the stimulated luminescence light 74 reflected by the dichroic mirror 67, and the stimulated luminescence light 74 is focused by the detection lens 75. The light enters the photomultiplier tube 7B. Furthermore, at the position where the stimulated luminescence light 74 is focused by the detection lens 75, an aperture plate 77 having an open lower part 7a having a size that allows only the stimulated luminescence light 74 within a range necessary for image information to pass through is arranged. . A part of the excitation light 80 incident on the stimulable phosphor sheet 1 is reflected on the sheet surface,
When this reflected light hits a member in the device such as a condensing lens and is reflected again and excites parts of the stimulable phosphor sheet 1 other than the predetermined laser beam irradiation position, stimulated luminescence light is generated from these parts. These stimulated luminescent lights pass through the condenser lens 73 and the detection lens 75, and are guided to a position different from the stimulated luminescent light emitted from a predetermined position. Therefore, these stimulated luminescent lights are cut by the aperture plate 77 and are prevented from entering the photomultiplier tube 76. By providing the aperture plate 77 in this way, this device can cut stimulated luminescence light generated by reflected excitation light and scattered excitation light in the stimulable phosphor sheet, allowing highly accurate reading of image information. can be done.

Note that the light is reflected on the stimulable phosphor sheet 1, and the condensing lens 7
It is conceivable that the excitation light BO that has passed through the photomultiplier tube 7B passes through the open lower part 7a of the aperture plate 77 together with the stimulated luminescence light 74.
An optical filter 78 that selectively transmits only light in the wavelength range of 4 is provided, and is designed to cut off the excitation light 60 that has passed through the open lower portion 7a. The photomultiplier tube 76 photoelectrically reads the incident stimulated luminescence light 74,
A read image signal S is output. This read image signal S is sent to a reading circuit 20 similar to that in the apparatus shown in FIG.
It is passed through a converter 22. Digitized image signal S
d is used for reproducing a radiation image as described above.

When the reading of the radiation image information is completed as described above, the platen 51 has moved to the position shown by the dashed line in FIG. 6, and is stopped at this position after the reading is completed. The roller 56 is then rotated in the opposite direction to that described above, and the stimulable phosphor sheet 1 is delivered from the platen 51 onto a sheet transport system (not shown).

As shown in FIGS. 7 and 8, an arc-shaped reference light source 80 is fixed at a position away from the platen 51 so as to form a substantially common cylindrical surface with the stimulable phosphor sheet 1 on the platen 51. has been done. This reference light source 80 has the configuration shown in FIG. 5 as an example, and emits reference light 81 having the same wavelength as the stimulated luminescence light 74. In addition, the deflection mirror 7 receives the output of the encoder 82 connected to the rotating shaft of the motor 72A.
A timing clock generation circuit 83 is provided which generates a timing clock CLK synchronized with the rotation of the motor 2, and this timing clock CLK is input to the CPU 27. C.P.
U27 operates the condenser lens 7 based on the timing clock CLK when the above-described image information is read.
3 faces the light source 80, the A/D
The signal Sd output by the converter 22 is taken in.

During the predetermined period, the reference light 81 of constant intensity emitted by the light source 80 is collected by the condensing lens 73 and detected by the photomultiplier tube 7B. The CPU 27 stores the value of the signal Sd that should be output when the reference light 81 with a constant intensity is detected, and the deviation between the stored signal value and the value of the signal Sd that is actually captured is determined by the CPU 27. The sensitivity of the photomultiplier tube 7B is set so that the above-mentioned deviation is eliminated by outputting a correction signal S5 corresponding to the deviation and controlling the high voltage Hv applied to the photomultiplier tube 76.

The sensitivity correction operation described above is performed for each main scan of the excitation light 60. By doing this, it is possible to prevent radiation image information from being read from a single stimulable phosphor sheet 1 while the light intensity lamp photocurrent characteristics of the photomultiplier tube 76 are largely fluctuating, and sensitivity correction is performed. Accuracy can be sufficiently increased.

Furthermore, in this embodiment, a large number of optical elements are interposed between the stimulable phosphor sheet 1 and the photomultiplier tubes 70 and 9, and by performing the above sensitivity correction, dirt etc. on these optical elements can be prevented. At the same time, it is possible to correct fluctuations in stimulated luminescence light detection efficiency due to

In each of the embodiments described above, the gain of the stimulated emission light reading system is changed by changing the high voltage applied to the photomultiplier tube, but in order to change the gain of this reading system, In addition, for example, the gain of an amplifier that amplifies the output of the photodetector may be changed.

In addition, the sensitivity correction operation of the photodetector is performed when the temperature near the light receiving surface of the photodetector changes by more than the set value, as in the first to third embodiments, that is, when the light intensity lamp photocurrent characteristic of the photodetector changes significantly. It may be carried out whenever possible, or it may be carried out every time the excitation light main scan is performed as in the fourth embodiment, or it may be carried out once every day when the radiation image information reading apparatus is started up.

Furthermore, if sensitivity correction is to be performed regularly every day as described above, a combination of a stimulable phosphor sheet with no recording and the aforementioned β-ray source should be used as the light source that emits the reference light. You can also do it. In other words, in that case,
First, the above-mentioned stimulable phosphor sheet is irradiated with visible light, etc. to release all of the accumulated radiation energy, then this sheet is irradiated with β-rays for a certain period of time, and then excitation light of a certain intensity is applied onto this sheet. What is necessary is to scan to emit stimulated luminescence light as a reference light having a constant intensity.

(Effects of the Invention) As explained in detail above, the radiation image information reading device of the present invention corrects the sensitivity of the photodetector by causing the photodetector to receive reference light having the same wavelength as the stimulated luminescence light detected by the photodetector. With this configuration, this sensitivity correction can be performed with extremely high accuracy in accordance with the actual usage conditions of the photodetector. Therefore, according to this apparatus, it is possible to read radiographic image information with extremely high accuracy, and when performing the quantitative measurement of the radiation dose described above, the accuracy of the total 11 PJ can be sufficiently increased.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing a radiation image information reading device according to a first embodiment of the present invention, FIG. 2 is a block diagram showing main parts of the radiation image information reading device, and FIGS. 3 and 4 are respectively , a block diagram showing the main parts of the apparatus according to the second and third embodiments of the present invention, FIG. 5 is a sectional view showing an example of a reference light source used in the apparatus according to the present invention, and FIG. 6 is a block diagram showing the main parts of the apparatus according to the second and third embodiments of the present invention. A perspective view showing a stimulable phosphor sheet holding means and a sub-scanning means of the device, and FIGS. 7 and 8 are respectively a perspective view and a schematic front view showing essential parts of the device of the fourth embodiment. 1... Stimulative phosphor sheet 2.59... Laser light source 3.60... Excitation light 4... Rotating polygon mirror 7
．． 74... Stimulated luminescence light 8... Light guide 9.76
...Photomultiplier tube 1O178...Filter 13.
...Endless belt 20...Reading circuit 22...
A/D converter 25...tungsten lamp 26
...Stabilized power supply 27...CPU28...
Photodiode 29...Light source light intensity detection circuit 30
... High voltage power supply 31 ... Temperature sensor 32.
81...Reference light 41...Shutter 42...
・Light amount stabilization circuit 44...Filter 45...β
Radiation source 4B...Scintillator 47...1
4C polymer 48...Scintillator particles 51.
...Platen 53...Screw rod 5
4...Motor 58...Scanning optical system 7
1... Spinner 72... Deflection mirror 73
...Condenser lens 75...Detection lens 77.
...Aperture plate 80...Reference light source (Fig. q) (Fig. q)

Claims (1)

[Claims] A stimulable phosphor sheet that stores and records radiation image information is irradiated with excitation light, and stimulated luminescence light is generated from a portion of the stimulable phosphor sheet that is irradiated with the excitation light. , in a radiation image information reading device that reads the radiation image information by photoelectrically detecting it with a reading system including a photodetector, a reference light having the same wavelength range as the stimulated luminescence light is applied to the photocathode of the photodetector. A light source device for irradiating, and means for adjusting the gain of the reading system so that when the photocathode is irradiated with the reference light, a predetermined output corresponding to the reference light intensity is obtained from the reading system. A radiation image information reading device characterized by: