JP2000284384A - Sn ratio inspecting method and radiation image reading machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure an SN ratio withoqt accumulating and recording a radiation image by using a phosphor sheet for inspecting an SN ratio having a phosphor layer incorporating fluorescent material emitting stimulated luminescence by the irradiation of stimulating light. SOLUTION: Not the ordinary phosphor sheet P but what is called an anti- stokes type phosphor sheet Pv having the phosphor layer incorporating the material (anti-stokes material) emitting the stimulated luminescence by the incidence of the stimulating light L even when the radiation is not accumulated and recorded (exposed) is used as the phosphor sheet for inspecting the SN ratio in order to measure the SN ratio. Thus, the SN ratio is measured without radiation exposure, and measurement of the SN ratio depending only on the image reading machine without being influenced by a radiation source or the phosphor sheet Pv is performed. As the utilizable anti-stokes material, known material is utilized in accordance with the wavelength of the stimulating light of the image reading machine and the wavelength of the stimulated luminescence from the ordinary phosphor sheet P.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a radiation image reader for reading a radiation image recorded on a phosphor sheet, which is used for radiation diagnosis and the like. Related to N ratio inspection.

[0002]

2. Description of the Related Art A radiation diagnostic system using a stimulable phosphor, such as FCR (Fuji Computed Radiography), has been put to practical use.

[0003] A stimulable phosphor (stimulable phosphor) means that when irradiated with radiation (X-ray, α-ray, β-ray, γ-ray, electron beam, ultraviolet ray, etc.), a part of the radiation energy is emitted. Accumulate,
Thereafter, when the phosphor is irradiated with excitation light such as visible light,
It is a phosphor that shows stimulated emission according to the stored energy. In the radiation diagnostic system using the stimulable phosphor, a radiation image of a subject such as a human body is recorded on a sheet having a stimulable phosphor layer (hereinafter, referred to as a phosphor sheet), and the phosphor sheet is excited by excitation light. Scans two-dimensionally to generate stimulated emission light, and photoelectrically reads the stimulated emission light to obtain an image signal. Based on the image signal, the radiation of the subject is displayed on a photographic photosensitive material or a display device such as a CRT. Output an image as a visible image (JP-A-55-12429, JP-A-56-1)
No. 1395).

Further, a system using a stimulable phosphor has many advantages, and is considered to be used not only in the field of medical diagnosis but also for flaw detection inspection of industrial products.
For example, if a transmitted radiation image such as a round bar or a steel pipe is reproduced in the same manner as above, the damaged portion has a lower radiation absorptivity than the other portions, and in the reproduced image, becomes darker than the surroundings. In addition, a damaged portion that cannot be observed from the outside can be detected.

In order to perform proper diagnosis and inspection using such a radiation image system, it is naturally preferable that the unnecessary noise in the reproduced image is as small as possible. One of the important factors is that the S / N ratio of the radiation image reader that reads the stored and recorded radiation images is appropriate.

Normally, the measurement of the S / N ratio in a radiation image reader (hereinafter, referred to as an image reader) for reading a radiation image of a phosphor sheet is performed by irradiating the phosphor sheet with radiation of a predetermined intensity to obtain a so-called solid image. This is performed by accumulating and recording a radiation image and analyzing an image signal (image data) obtained by reading the solid radiation image. However, such a method for measuring the S / N ratio requires irradiating the phosphor sheet with radiation to record a solid radiation image, which is troublesome. In addition, when the measured S / N ratio is not appropriate, it cannot be determined whether the cause is the radiation source, the phosphor sheet, or the image reader, and it is troublesome to perform an appropriate treatment. There is also a problem that it takes.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a radiation image reader for reading a radiation image photographed on a phosphor sheet (IP: imaging plate). The S / N ratio can be measured without storing and recording the radiation image on the phosphor sheet, and the S / N ratio caused only by the radiation image reader is measured to determine the state of the radiation image system. It is an object of the present invention to provide an S / N ratio inspection method for a radiation image reader and a radiation image reader, which enable the user to also grasp the appropriateness.

[0008]

In order to achieve the above object, a method for inspecting an S / N ratio according to the present invention comprises the steps of: reading a radiation image stored and recorded on a phosphor sheet having a stimulable phosphor layer; A phosphor layer containing a phosphor material that emits stimulated emission light by irradiation of excitation light even when radiation is not accumulated.
By using an S / N ratio inspection phosphor sheet, the S / N ratio inspection phosphor sheet is irradiated with excitation light, and the emitted stimulated emission light is read photoelectrically to obtain image data. Provided is an S / N ratio inspection method, wherein an S / N ratio for radiation image reading is calculated using data. In this S / N ratio inspection method, at least one of a plurality of S / N ratio inspection phosphor sheets having different stimulated emission light amounts and an S / N ratio inspection phosphor sheet having regions having different stimulated emission light amounts are used. Is preferred.

Further, the radiation image reader of the present invention has an optical system for irradiating a phosphor sheet having a stimulable phosphor layer with excitation light, and a radiant light emitted from the stimulable phosphor layer by the irradiation of the excitation light. Reading means for photoelectrically reading the emitted light;
A processing unit configured to perform predetermined processing on the image signal read by the reading unit to generate image data, a reference light source that emits a predetermined amount of inspection light corresponding to the stimulated emission light to the reading unit,
Using the image data obtained by processing the inspection light read by the reading means by the processing means, the S
And a S / N ratio calculating means for calculating the / N ratio.

Further, another aspect of the radiation image reader according to the present invention is an optical system for irradiating a phosphor sheet having a stimulable phosphor layer with excitation light, and an optical system for irradiating the stimulable phosphor layer with the excitation light. Reading means for photoelectrically reading the emitted stimulated emission light; processing means for performing predetermined processing on the image signal read by the reading means to generate image data; and a processing means having a predetermined intensity corresponding to the image signal. A reference signal source for inputting a reference electric signal, and S / N ratio calculating means for calculating an S / N ratio for radiation image reading using image data obtained by processing the reference electric signal by the processing means. A radiation image reader characterized by having:

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an S / N ratio inspection method and a radiation image reader of a radiation image reader according to the present invention will be described.
The present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 shows the S / S of the radiation image reader of the present invention.
FIG. 1 shows a conceptual diagram of an example of a radiation image recording / reading apparatus suitable for carrying out an N ratio inspection method and using the radiation image reader of the present invention. Radiation image recording and reading device 10 shown in FIG.
The recording / reading device 10 constitutes a radiation diagnostic system using the above-described phosphor sheet, and basically includes a standby unit 12 for the phosphor sheet P and an imaging unit 14.
, Reading unit 16, erasing unit 18, image signal processing unit 2
0. In the recording reader 10, a radiation image reader (hereinafter, referred to as an image reader)
Basically, it is configured by the reading unit 16 and the processing unit 20.

The standby section 12 stores a phosphor sheet P which has not been exposed (a radiographic image has not been captured).
When storing and recording (photographing) a radiographic image, the transport roller pair 2
4. Conveying means 2 consisting of rollers and endless belts
6 and the conveying roller pair 28 to convey the image to the photographing unit 14.

The photographing section 14 comprises a holding table 30 for the phosphor sheet P which can be rotated about a shaft 30a at the lower end,
2 and a radiation source 34. When the phosphor sheet P is transported to the imaging unit 14 by the transport roller pair 28, the holder 30 holds the phosphor sheet P, and then,
As shown by the arrow, the holding table 30 rotates around the axis 30a in the left direction in the figure, and the phosphor sheet P is moved to the photographing table 32.
(Back side to the subject). Next, radiation (X-rays) is emitted from the radiation source 34, and a radiation image is captured (stored and recorded) on the phosphor sheet P.

When the photographing is completed, the holding table 30 is rotated rightward in the figure to separate the phosphor sheet P from the photographing table 32,
Next, the phosphor sheet P is moved upward by moving means (not shown), and is held between the transport roller pairs 35. The phosphor sheet P is further conveyed by conveyance means 44 and a guide 46 composed of an endless belt and rollers, and sent to the sub-scanning (conveyance) roller pair 38 of the reading unit 16.

The reading section 16 includes a scanning optical system 36, a light guide 40, a photomultiplier (photomultiplier) 42, and an image reader of the recording and reading apparatus 10 in addition to the sub-scanning roller pairs 38 and 38. A reference light source 22 for measuring the S / N ratio. The phosphor sheet P conveyed to the reading section 16 is conveyed in the sub-scanning direction (right direction in the drawing) by the sub-scanning roller pair 38, and is emitted from the scanning optical system 36 in the main scanning direction orthogonal to the sub-scanning direction. Scanning is performed two-dimensionally by the excitation light L deflected in the direction (perpendicular to the page). From the phosphor sheet P scanned by the excitation light, stimulated emission light is generated according to the stored and recorded radiation image. The photostimulated light is propagated by a light guide 40, and after components other than the photostimulated light are removed by a filter, the photostimulated light is incident on a photomultiplier 42, photoelectrically read, and processed as an image signal of a radiation image. 20.

When measuring the S / N ratio of the image reader in the recording / reading apparatus 10, the reference light source 22 is used as an inspection light corresponding to the stimulated emission light, specifically, at the same wavelength or as the stimulated emission light. An inspection light of a predetermined amount and a wavelength approximate to the light guide 4
The light is irradiated to the incident portion of the stimulable emission light of 0. As the reference light source 22, a light source according to the stimulating light emitted from the phosphor sheet to be used may be appropriately selected. For example, if the stimulating light is blue, the light extends in the main scanning direction. An LED array that emits light is exemplified.

The reference light source 22 is configured to be movable so that S
The inspection light may be moved to a position where it can enter the light guide 40 only at the time of measuring the / N ratio, or the stimulating light emitted from the phosphor sheet P does not interfere with the light guide 40. If so, it may be fixed at a predetermined position.
Further, for the same reason as the S / N ratio inspection phosphor sheet Pv described later, the reference light source 22 may be configured to emit a plurality of light amounts of inspection light, and divided in the main scanning direction. You may comprise so that the test | inspection light of mutually different light quantities may be emitted in several area | regions. The light amount ratio at this time may be the same as that of the phosphor sheet Pv.

The phosphor sheet P for which the reading of the radiation image has been completed is conveyed to the erasing section 18 by the guide 48 and the conveying roller pair 50 and is irradiated with the erasing light emitted from the erasing lamp 52, and the remaining radiographic image is left. Are erased to form an unexposed phosphor sheet P, which is conveyed to the standby unit 12 by the conveying roller pair 54, the conveying means 56 including endless belts and rollers, the conveying means 26, and the conveying roller pair 24.

As shown in FIG. 2, the processing unit 20
og converter 60, amplifier 62, anti-aliasing filter 64, A / D (analog / digital) converter 66,
The image processing section 68 includes a reference signal source 70 and an S / N ratio calculating section 72.

When reading a normal radiation image (and measuring the S / N ratio using the reference light source 22), the image signal of the radiation image output from the photomultiplier (PMT) 42 is converted into a log converter 60. After being amplified by the amplifier 62 and amplified by the amplifier 62, the high frequency component causing the aliasing is removed by the anti-aliasing filter 64, and then converted by the A / D converter 66 into digital image data.

The reference signal source 70 outputs a reference electric signal of a predetermined strength corresponding to the image signal to the Log converter 60 when measuring the S / N ratio of the image reader. In the radiation image reader of the present invention, the input of the reference electric signal is not limited to the Log converter 60. For example, the amplifier 62, the anti-aliasing filter 64, and the A
To one of the / D converters 66, an electric signal of a predetermined strength corresponding to the image signal inputted thereto may be inputted as a reference electric signal.

The S / N ratio calculator 72 includes an A / D converter 66
S / N of the image reader using the image data processed in
The ratio is calculated. The S / N ratio calculator 7
2. The operation of the reference power supply 70 and the reference signal source 70 will be described later in detail.

At the time of ordinary radiation image reading, the image data processed by the A / D converter 66 is then sent to an image processing section 68, where predetermined image processing such as gradation adjustment, density correction, and sharpness (sharpening) processing is performed. Is output to the output unit O, and is provided for display by a display means such as a CRT (Cathode Ray Tube), output as a hard copy by a printer, and the like. If necessary, image data for calculating the S / N ratio may be output from the image processing unit 68 to the output unit O and displayed on a CRT or the like. In this case,
The image processing unit 68 may output the image data without processing the image data.

The S / N ratio inspection method of the present invention uses such an image reader (the reading unit 16 and the processing unit 20 in the illustrated example).
In the measurement of the S / N ratio, even if the ordinary phosphor sheet P is not used and the radiation is not accumulated and recorded (irradiation), the S / N ratio is measured by the incidence of the excitation light L. A so-called anti-Stokes type phosphor sheet Pv having a phosphor layer containing a material that emits emitting light (anti-Stokes material) is used as a phosphor sheet for S / N ratio inspection. By using such an anti-Stokes type phosphor sheet Pv, the S / N ratio can be measured without irradiating radiation, and furthermore, it is not affected by the radiation source or the phosphor sheet Pv. Measurement of the S / N ratio depending only on the image reader can be performed.

In the present invention, usable anti-Stokes materials are not particularly limited, and known materials can be selected according to the wavelength of the excitation light of the image reader and the wavelength of the stimulating light of the ordinary phosphor sheet P. Various available. For example, 632.8n emitted from a He-Ne laser as excitation light
m laser beam, γ-AlF ₃ : F
e ³⁺ is exemplified.

When a laser beam having a wavelength of 850 nm emitted from a GaAs semiconductor laser is used as the excitation light, a material represented by the following general formula, M ^I , disclosed in JP-A-61-72089 is used. _{^{X · aM II X 2 · bM}} III X 3: cA ( in the general formula, M ^I is, Li, Na, K, Rb
And Cs and at least one of Rb and Cs. M ^II is Be, M
g, at least one divalent metal selected from Ca, Sr, Ba, Zn, Cd, Cu and Ni. M ^III is S
c, Y, La, Ce, Pr, Nd, Pm, Sm, Eu,
Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, A
One or more trivalent metals selected from 1, Ga, and In. X is one or more selected from F, Cl, Br and I, and three Xs may be the same or different from each other. A is one or more selected from TI, Na, Ag, and Cu. Also, 0 ≦ a ≦ 1 and 0 ≦ b ≦ 0.
5 and 0 ≦ c ≦ 0.2. ) And JP-A-62-2
Material represented by the following general formula disclosed in 209187 ^{JP, M I X · aM II X} 2: bTl ( in the general formula, M ^I is at one or more selected Na, K, from Rb and Cs M ^II is Mg, C
a, at least one divalent metal selected from Sr, Ba, Zn, Cd, Cu and Ni. X is F, Cl, B
at least one selected from r and I, which may be the same or different. Also, 0 ≦ a ≦ 1 and 0 ≦ b ≦
0.5. ) Is available.

In the S / N ratio inspection method of the present invention, it is preferable to measure the S / N ratio by using different amounts of photostimulated light. In reading a radiation image, there are many causes of noise, but the influence of noise from each noise source differs depending on the amount of photostimulated light. For example, when the amount of stimulated emission is small, noise due to light such as photon noise (fluctuation of the excitation light L) and the light collection efficiency of the stimulated emission is dominant, and the influence of electrical noise is small. Conversely, when the amount of stimulated emission is large, the influence of noise due to light is small and the influence of electrical noise is large. Therefore, the S / N ratio is determined using photostimulated light having different light quantities.
By measuring the ratio, both noise due to light and electrical noise can be detected, and inspection accuracy can be further improved.

In the present invention, the measurement of the S / N ratio using photostimulated light having different light quantities may be performed using a plurality of phosphor sheets Pv having different photostimulated light quantities. May be performed using a phosphor sheet Pv having regions having different amounts of stimulated emission from each other. In the measurement of the S / N ratio, the light amount ratio of the stimulated emission light is 1:
About 10 to 1: 100 is preferable. The amount of stimulated emission of the phosphor sheet for S / N ratio inspection may be adjusted according to the amount of the anti-Stokes material contained in the phosphor layer, and may be adjusted according to the type of the anti-Stokes material contained in the phosphor layer. It may be an adjusted one or a combination of both.

An example of a method for inspecting the S / N ratio of a radiation image reader using such a phosphor sheet Pv will be described below.
This will be described with reference to the recording and reading device 10 shown in FIG.
That is, in the illustrated example, the S / N ratio of the reading unit 16 and the processing unit 20 constituting the image reader is measured.

First, the phosphor sheet Pv for S / N ratio inspection
Is loaded at a predetermined position of the standby unit 12, and then the execution of the S / N ratio inspection is instructed by, for example, selecting a mode.
In response, the recording and reading device 10 conveys the phosphor sheet Pv from the standby unit 12 to the imaging unit 14 and conveys to the reading unit 16 without imaging a radiation image. Phosphor sheet Pv
Is transported to the reading unit 16, the phosphor sheet Pv is two-dimensionally scanned by the excitation light L as described above, and emits stimulated emission light corresponding to the anti-Stokes material contained in the phosphor layer. Occurs. The stimulated emission light is propagated by the light guide 40, is photoelectrically read by the photomultiplier 42, and is sent to the processing unit 20 as an image signal, similarly to the radiation image stored and recorded on the normal phosphor sheet P. Can be

When the S / N ratio is measured using such a phosphor sheet Pv, and when a radiation image stored and recorded on a normal phosphor sheet P is read, the reference light source 22 and the reference signal source 70 are used. , Does not act (drive).

The phosphor sheet Pv for which reading has been completed is
The data is sent to the standby unit 12 via the erasing unit 18 and thereafter removed from the recording / reading device 10 if unnecessary.

The image signal sent to the processing unit 20 is converted into an L signal by the Log converter 60 in the same manner as when reading a normal radiographic image.
The A / D converter 6 performs og conversion, amplifies the amplified signal by the amplifier 64, and
The digital image data is converted into digital image data at 6 and sent to the S / N ratio calculator 72.

The S / N ratio calculator 72 includes an A / D converter 66
Extract the necessary image data from the image sampling area of the image data supplied from, using this image data,
The S / N ratio for image reading is calculated. In the present invention, preferably, the S / N ratio is RMS (root mean square).
And the granularity of the image such as the Wiener spectrum. The calculation of the graininess may be performed by a known method.

The S / N ratio calculation unit 72 determines whether the S / N ratio of the reading unit 16 and the processing unit 20 is appropriate based on the calculated granularity, and uses the result or further calculated granularity in image processing. This is supplied to the unit 68, and this is displayed on the display means of the output means O. In the present invention, the determination as to whether the S / N ratio of the radiation image reader (the reading unit 16 and the processing unit 20) is appropriate may be appropriately determined in accordance with the required reading accuracy and the like, and is not particularly limited. However, when the S / N ratio deteriorates by 10% or more from the specified value (specified range), the S
It is preferable to determine that the / N ratio is inappropriate.

As described above, the recording / reading apparatus 10 using the radiation image reading apparatus of the present invention is an image reading apparatus (reading section 16).
And a reference light source 22 and a reference signal source 70 for inspecting the S / N ratio of the processing unit 20). Hereinafter, the inspection of the S / N ratio using these will be described, and the radiation image reader of the present invention will be described in more detail.

Similarly, when performing the S / N ratio inspection using the reference light source 22, the execution of the S / N ratio inspection using the reference light source 22 is instructed by selecting a mode or the like. In response, the recording and reading device 10 conveys the unphotographed phosphor sheet P from the standby unit 12 to the photographing unit 14 and conveys it to the reading unit 16 without photographing a radiation image. When the phosphor sheet P is conveyed to the reading unit 16, the reference power supply 22 is driven at a predetermined timing, and a predetermined amount of inspection light corresponding to the stimulated emission light is incident on the light guide 40. Irradiate mouth. When measuring the S / N ratio using the reference light source 22, the scanning optical system 36 is not driven, and the excitation light L is not irradiated on the phosphor sheet P. The inspection light emitted from the reference power supply 22 is propagated by the light guide 40, is read photoelectrically by the photomultiplier 42, and is sent to the processing unit 20 as an image signal similar to the radiation image stored and recorded on the phosphor sheet P. Sent.

In the present invention, S using the reference power source 22
When the / N ratio is measured, the phosphor sheet P is not necessarily transported. However, in a normal radiation image reader, various operations are usually performed in accordance with the transportation of the phosphor sheet P. Therefore, even when the S / N ratio is measured using the reference power supply 22, the operation is not performed. By adopting a configuration in which the phosphor sheet P for exposure is conveyed, there is no need to perform an operation setting such that the processing unit 20 or the like operates even without the phosphor sheet P, which is advantageous in terms of apparatus design. .

The phosphor sheet P that has passed through the reading unit 16 is
The sheet is sent to the standby section 12 via the erasing section 18 and held as an unused phosphor sheet P. The erasing lamp 52 may be driven to irradiate the erasing light as needed.

The image signal (inspection light signal) sent to the processing unit 20 is Lo, as in the case of reading a normal radiation image.
The data is log-converted by the g-converter 60, amplified by the amplifier 64, converted by the A / D converter 66 into digital image data, and sent to the S / N ratio calculator 72. At this time, the reference signal unit 70 does not operate.

The S / N ratio calculation unit 72 performs the same
The necessary image data corresponding to the image sampling area is extracted from the image data supplied from the A / D converter 66, and the S / N ratio (granularity) of the image reading is calculated using this image data. The S / N ratio calculation unit 72 determines whether the S / N ratio of the reading unit 16 and the processing unit 20 is appropriate based on the calculated granularity, and transmits the result or further calculated granularity to the image processing unit 68. And this is the output means O
Is displayed on the display means. The criterion and the like may be the same as in the above-described example.

According to this embodiment, the S / N ratio caused by reading the stimulated emission light after reading the stimulated emission light is measured, not depending on the characteristics of the radiation source and the phosphor sheet P, nor on the scanning optical system of the excitation light L. The S / S of the radiation image reader
It is possible to quickly clarify and solve the cause when an abnormality occurs in the N ratio.

On the other hand, when the S / N ratio inspection using the reference signal source 70 is performed, similarly, the execution of the S / N ratio inspection using the reference signal source 70 is instructed by selecting a mode or the like. In response to this, similarly to the measurement of the S / N ratio using the reference power supply 22, the recording / reading device 10 conveys the unphotographed phosphor sheet P from the standby unit 12 to the imaging unit 14 and The sheet is conveyed to the reading unit 16 without taking an image.

When the phosphor sheet P is conveyed to the reading section 16, the reference signal source 70 is driven at a predetermined timing to
The reference electrical signal is supplied to the OG converter 60. When inspecting the S / N ratio using the reference signal source 70, the scanning optical system 36
And the reference power supply 22 is not driven. In addition, reference power supply 2
Similarly to the measurement of the S / N ratio using No. 2, the transport of the phosphor sheet P is not necessarily required in this embodiment,
By adopting a configuration in which the phosphor sheet P is transported, there is also an advantageous aspect in terms of device design.

The phosphor sheet P passing through the reading unit 16 is
The sheet is sent to the standby section 12 via the erasing section 18 and held as an unused phosphor sheet P. The erasing lamp 52 may be driven to irradiate the erasing light as needed.

The reference electric signal input to the Log converter 60 is Log-converted by the Log converter 60 in the same manner as the image signal photoelectrically read by the photomultiplier 42 in the ordinary radiation image reading, and the amplifier 64 , And is converted into digital image data by the A / D converter 66 and sent to the S / N ratio calculation unit 72.
S / N ratio of image reading (granularity) in the same manner as in the above example
Is calculated to determine whether the S / N ratio is appropriate, and the result or further calculated granularity is displayed on the display means of the output means O. The criterion and the like may be the same as in the above-described example.

According to this aspect, the S / N caused by only the electric signal processing system, which does not depend on the radiation source and the phosphor sheet P, the scanning optical system of the light beam, and the reading system of the stimulating light is also used.
The ratio can be measured, and the cause of an abnormality in the S / N ratio of the radiation image reader can be clarified and solved quickly.

The S / N ratio inspection of the radiation image reader according to the present invention or the conventional S / N ratio inspection performed by recording a solid radiation image on a normal phosphor sheet P may be appropriately combined. By doing so, it is possible to more appropriately detect the cause of the S / N ratio deterioration of the radiation imaging system.

As an example, first, the S / N ratio is measured using a reference electric signal (hereinafter referred to as inspection A). If an abnormality is found in the S / N ratio, a failure in the electric signal processing system, in the illustrated example, a failure in the processing unit 20 is estimated. Next, the S / N ratio is measured using the inspection light emitted from the reference power supply (hereinafter, referred to as inspection B). Inspection A
Is normal and the S / N ratio is abnormal in the inspection B, the failure of the photoelectric conversion unit such as the photoelectric conversion element and its power supply, the light guide 40 and the photomultiplier 42 in the illustrated example. And the failure of the high-voltage power supply. Next, S / N having an anti-Stokes type stimulable phosphor layer
The S / N ratio is measured using a phosphor sheet for ratio inspection (hereinafter referred to as inspection C). If the results of the inspections A and B are normal and the S / N ratio is abnormal in the inspection C, it is estimated that the optical system of the excitation light is defective, and in the illustrated example, the scanning optical system 36 is defective. You. Inspections A, B and C for abnormalities
In any case, no abnormality was observed in the S / N ratio.
If an abnormality is found in the inspection using a phosphor sheet that has taken a solid radiation image, it is estimated that the X-ray imaging apparatus or the phosphor sheet is defective, and in the illustrated example, the radiation source 34 is defective.

As described above, the S / N of the radiation image reader of the present invention
Although the ratio inspection method and the radiation image reader have been described in detail, the present invention is not limited to the above embodiment, and various improvements and changes may be made without departing from the scope of the present invention. Of course. For example, the illustrated recording / reading apparatus 10 includes a reference light source 22 that emits inspection light for inspecting the S / N ratio, and a reference signal source 70 that supplies a reference electric signal for inspecting the S / N ratio. Although it has both, the radiation image reader of the present invention is not limited to this, and may have only one of them.

[0052]

As described in detail above, according to the present invention, the S / N ratio of a radiation image reader for reading a radiation image or the like photographed on a phosphor sheet is determined by changing the S / N ratio on the phosphor sheet. Measurement can be performed without recording, and the S / N ratio caused only by the radiation image reader can be measured, so that the state of the radiation imaging system can be properly grasped.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an example of a radiation image recording / reading device using a radiation image reading device of the present invention.

FIG. 2 is a block diagram of a processing unit of the radiation image recording and reading apparatus shown in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 (radiation image) recording / reading device 12 standby unit 14 imaging unit 16 reading unit 18 erasing unit 20 processing unit 22 reference light source 24, 28, 35, 50, 52 transport roller pair 26, 44, 54 transport unit 30 holding unit 32 imaging Table 34 Radiation source 36 Scanning optical system 38 Sub-scanning roller pair 40 Light guide 42 Photomultipliers 46, 48 Guide 52 Erase lamp 60 Log converter 62 Variable gain amplifier 64 Anti-aliasing filter 66 A / D converter 68 Image processing unit 70 Reference signal source 72 S / N ratio calculator P phosphor sheet Pv phosphor sheet for S / N ratio inspection

Claims (4)

[Claims] An S / N ratio inspection method for a radiation image reader for reading a radiation image stored and recorded on a phosphor sheet having a stimulable phosphor layer, the method comprising the steps of: An S / N ratio inspection phosphor sheet having a phosphor layer containing a fluorescent material that emits stimulated emission light upon irradiation is used, and the S / N ratio inspection phosphor sheet is irradiated with excitation light to emit light. Image data is obtained by photoelectrically reading the stimulated emission light,
An S / N ratio inspection method comprising calculating an S / N ratio for reading a radiation image using the image data. 2. The method according to claim 1, wherein at least one of a plurality of S / N ratio inspection phosphor sheets having different amounts of stimulated emission light and an S / N ratio inspection phosphor sheet having regions having different amounts of stimulated emission light are used. The described S / N ratio inspection method. 3. An optical system for irradiating a phosphor sheet having a stimulable phosphor layer with excitation light, and a reading device for photoelectrically reading stimulated emission light emitted from the stimulable phosphor layer by irradiation with the excitation light. Means for performing predetermined processing on image signals read by the reading means to generate image data; a reference light source for projecting a predetermined amount of inspection light corresponding to stimulated emission light to the reading means; S / N ratio calculation means for calculating an S / N ratio for reading a radiation image using image data obtained by processing the inspection light read by the means by the processing means. Reader. 4. An optical system for irradiating a phosphor sheet having a stimulable phosphor layer with excitation light, and reading for photoelectrically reading stimulated emission light emitted from the stimulable phosphor layer by irradiation of the excitation light. Means for performing predetermined processing on the image signal read by the reading means to generate image data; a reference signal source for inputting a reference electric signal having a predetermined strength corresponding to the image signal to the processing means; A radiation image reader comprising: an S / N ratio calculating unit that calculates an S / N ratio for reading a radiation image using image data obtained by processing the electric signal by the processing unit.