JP2717653B2 - Radiation image information reading method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a stimulable phosphor on which radiation image information is recorded.
An image signal for reproducing a visible image from a recording medium such as a sheet
Regarding the method of reading radiological image information to perform main reading
In particular, reproduction can be performed based on a read image signal.
In the visual image (reproduced image), depending on the photographing position of the subject
The density of the region of interest in the subject is prevented from changing.
Radiation image information reading method that can be stopped
It is. (Prior art) Radiation (X-ray, α-ray, β-ray, γ-ray,
Electron beam, ultraviolet rays, etc.)
Part of the light is accumulated in the phosphor, and this phosphor
Irradiates with the excitation light of
It is known that phosphors emit photostimulated light.
Phosphors exhibiting various properties are called storage phosphors (stimulable phosphors).
Devour. Utilizing this stimulable phosphor, radiation of a subject such as a human body
The line image information is temporarily recorded on the sheet of the stimulable phosphor,
Scanning the stimulable phosphor sheet with excitation light such as laser light
Generates stimulating light and photoelectrically reads the resulting stimulating light.
And perform a real reading to obtain an image signal for reproducing the visible image.
There is no image in the book reading image signal obtained by this book reading.
Image processing is performed, and based on the image signal on which the image processing has been performed.
On recording materials such as photographic photosensitive materials and display devices such as CRTs
Radiation image information to output a body radiation image as a visible image
Report recording and playback system has already been proposed by the applicant
I have. (For example, JP-A-55-12429 and JP-A-59-11395.) In the above-described system, the subject and the photograph
Due to fluctuations in shadow areas or fluctuations in radiation exposure
Radiation energy level range stored and recorded on the sheet
Fluctuations occur. However, in the above system, individual
The recorded image information stored in the sheet in the image,
The radiation recorded and recorded on the sheet in each individual image above
Know the range of the line energy level, etc.
An image reading image determined appropriately based on the recorded image information of the image
According to the reading conditions such as
By performing the main reading, the above-described storage in each image is performed.
Evil due to variation in radiation energy level range recorded
Visible image with excellent observation and interpretation suitability that is not affected, ie, example
For example, if the necessary subject image information is always
A visible image displayed in the range can be obtained. In the above system,
A visual image suitable for diagnostic purposes
In order to obtain an image, the imaging region (head, chest,
Part, abdomen, etc.) and imaging method (simple imaging, contrast imaging, etc.)
Image processing conditions such as gradation processing conditions determined based on the
Image processing is performed. However, for example, before the book reading
Appropriate decision based on the recorded image information of each image as described above.
If the scanning is not performed according to the specified reading conditions,
The above-mentioned image processing conditions include the above-described imaging parts and imaging methods.
Recorded image information of individual images, not just information
It is desirable to take this into account in consideration of
Is suitable for diagnostic purposes and necessary image information
Obtains a visible image with excellent observation and reading suitability displayed in the density range
Can be Prior to such book reading and image processing, recorded image information
Japanese Patent Application Laid-Open No. 58-67240 discloses a method for determining
Known methods are known. This method is used for reproducing the visible image.
The excitation light to be illuminated during the main reading
Prior to the book reading, using a lower level of excitation light.
Recorded on the stimulable phosphor sheet in advance
This is a read-ahead for reading image information.
The recorded image information obtained by the
Conditions or other conditions based on the pre-read image signal
Determines the image processing conditions. The excitation light used for pre-reading here is used for main reading.
The lower level than the excitation light
Of the excitation light per unit area of the stimulable phosphor sheet
That the effective energy is smaller than that of the book
means. Also, only the image processing conditions are determined based on the recorded image information.
In the case of setting, the recorded image information is grasped before the image processing.
In this case, the recorded image information itself
Since the book-reading image signal has already been obtained,
Image processing conditions can be determined based on the image signal,
It is not always necessary to perform prefetching as described above. (Problems to be solved by the invention) However, as described above, reading of radiation image information
Once the conditions and / or image processing conditions are determined, the same
When shooting a subject in different positions,
The density of the region of interest in the subject changes in the reproduced image
Sometimes. The following explains this in detail
I will tell. For example, to diagnose the thoracic spine, as shown in Appendix 2A
When the chest is photographed from the side, as shown in Figure 2B
Consider the case of shooting from a surface. In the case of frontal photography, the area of interest
The thoracic vertebra K, which is a region, overlaps the mediastinal
Therefore, the accumulated radiation of the thoracic spine in the stimulable phosphor sheet
The dose is low and this area is the low luminescence area (see Figure 3A).
See the histogram of the read image signal shown in FIG. One side shot
In the case of thoracic vertebra K, it overlaps with the lung field where radiation is easily transmitted
In the stimulable phosphor sheet, the accumulated radiation of the thoracic spine
The light emission is high, and this area becomes the high light emission area (see FIG. 3B).
Stogram). And in the case of front view, it is also side view
In the case of shadow, the image signal read from the stimulable phosphor sheet
Since the maximum value Smax and the minimum value Smin do not change much,
One of the decision methods based on recorded image information
Based on the maximum value Smax and minimum value Smin of the read image signal
Reading conditions and / or image processing determined by the method
The conditions are almost the same in both cases. So this
Image under such reading conditions and / or image processing conditions
After reading and obtaining a reconstructed image, the thoracic spine is
Shadow images have relatively low density, while side images are taken
The density of the image becomes relatively high. These phenomena are limited to the above-mentioned parts and photographing positions
The part where radiation absorption is particularly high or low
Overlapping or not overlapping the region of interest due to differences in shadow position
Ordinarily occurs when the As described above, the region of interest depends on the photographing position of the subject.
In some cases, it is difficult to make a diagnosis using radiographic images.
You. Such a problem is caused by the accumulation of radiation image information.
Reads the image information from a recording medium other than the phosphor sheet
This can occur when a reproduced image is obtained. Therefore, in the present invention, the subject is recorded by changing the photographing positions.
Recorded from a recording medium such as a different stimulable phosphor sheet.
When reading the radiation image information and reproducing the radiation image,
The density of the region of interest in the reproduced image is
Radiation image information reading that can be aligned uniformly to each other
It is intended to provide a method. (Means for Solving the Problems) The radiographic image information reading method of the present invention is as described above.
At the time of reading the recording medium
Reading conditions and / or
Processing conditions for image processing of read book image signals
Is obtained by reading image information recorded on the recording medium.
To be determined based on the image signal for determining the conditions
A radiographic image information reading method, wherein a predetermined condition in the recording medium is determined from the image signal for condition determination.
The image signal relating to the partial area of the position is extracted, and
Calculate the representative value of the image signal related to the area, and the maximum or minimum value of the image signal
A predetermined discrimination value indicating the relationship between the characteristic value of
Therefore, the reading conditions and / or image processing are performed based on the discrimination value.
In which the processing conditions are determined.
You. As the representative value described above, an image signal of a partial area
Average, maximum or minimum values can be used
You. As the discrimination value, for example,
Use the average value Save of the image signal for the area to determine the conditions
The maximum value Smax and the minimum value Sm as characteristic values of the image signal
When in is used, a value such as Q = (Save−Smin) / (Smax−Smin) can be used. The “recording medium” in the above refers to the radiographic image information.
Information that can be recorded, and as an example,
Phosphor sheet, but not necessarily
However, the present invention is not limited to this. In addition, “book reading” in the above means that
Reading image signal for visual image reproduction, accumulation
This is also used for recording media other than the conductive phosphor sheet.
Can be. Further, the “reading condition” in the above refers to the reading means.
Between input and output, for example, if the recording medium
In the case of a body sheet, the input (photostimulated light emission)
Affects the relationship between light) and output (image signal level)
A general term for various conditions, such as reading gain
(Sensitivity), recording scale factor (latency), etc.
means. Further, the “image processing condition” in the above refers to an image processing condition.
Means that affect the relationship between input and output in
This is a general term for conditions such as gradation processing conditions and space.
Means frequency processing conditions. The “image signal for condition determination” in the above is
When determining reading conditions and / or image processing conditions
An image signal provided as a material and recorded on the recording medium.
Means image signal obtained by reading recorded image information
For example, the pre-read image signal and the main read image signal
Can be used as an image signal for condition determination of
It is not limited to them. Note that the pre-read image signal
Signal is used as the condition determination image signal.
Scanning conditions and / or image processing conditions
However, if the actual image signal is used, the image processing conditions
Can not decide. Also, “determined based on the discrimination value” means that
If you decide based on only, other things
For example, if the above-mentioned imaging part, imaging method or recorded image
This includes the case where it is determined based on the appropriate characteristic value.
You. In addition, the above “reading conditions and / or image processing conditions”
"Determination" is based on the discrimination value, that is, using the discrimination value
What method is used to determine what to do
The specific method is not specified at all.
No. (Action) Includes a specific region of interest, and shooting positions differ from each other
Images usually have their own patterns.
That is, in the example of FIGS. 2A and 2B described above,
The thoracic vertebra K is difficult to pass through radiation
Hiss in the radiation field
On the tomogram, the thoracic spine is located in the low light emission area (Fig. 3A).
On the other hand, in the side view of FIG. 2B, the thoracic spine K
Because it does not overlap with the pulse, it overlaps with the lung field where radiation can pass easily,
On the histogram in the irradiation field,
Higher than the diaphragm and apex of the lung (pulmonary field near the shoulder)
Indicates the amount of light emission. And the diaphragm and apex of the lung
Positioned in the off position. So this
In this case, the partial area P from which the condition determination image signal is
If it is set at almost the center of
The amount of emitted light is generally less than in the image of FIG.
It is higher in the image in Figure 2B (that is, the average value Save
Is higher). Therefore, for example, the aforementioned discrimination value Q
Is greater in FIG. 2B than in FIG. 2A.
Therefore, by obtaining this discrimination value Q,
Be able to determine whether the photographing position is front or side
become. Therefore, when the discrimination value Q is relatively large,
On the other hand, the discrimination value Q is relatively small so as to lower the density of the reproduced image.
If the size is small, set the reading conditions and
And / or image processing conditions, it is a region of interest
The density of the thoracic spine was compared between the front and side views.
It is possible to make them evenly equal. (Effect of the Invention) Therefore, as described above, the recording medium is converted from the image signal for determining the condition.
Extracting an image signal relating to a partial region at a predetermined position in the body,
A representative value of the image signal in the partial area is obtained,
Where the relationship between the value and the characteristic value of the image signal for condition determination is shown.
Reading conditions and / or image processing based on fixed discrimination values
According to the invention for determining the conditions, the interest in the reproduced image
It is necessary to make the density of the area constant with each other regardless of the shooting standard.
Can be. (Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
I will tell. FIG. 1 shows one embodiment of the radiation image information reading method according to the present invention.
Example of a radiation image information recording / reproducing system using the embodiment
It shows. This radiation image information recording and reproduction system
Basically, the radiation image capturing unit 20 and the read-ahead reading unit 3
0, a main reading section 40, and an image reproducing section 50.
Have been. In the radiation image capturing unit 20, for example, X-ray
From a radiation source 100 such as a tube to the subject (examinee) 101
Then, the radiation 102 is irradiated. Transmitted through this subject 101
At the position where the radiation 102 is irradiated, as described above,
A stimulable phosphor sheet 103 for storing radiation energy is arranged.
The stimulable phosphor sheet 103 transmits
Radiation image information is stored and recorded. In this way, the radiation image information of the subject 101 is recorded.
The stimulable phosphor sheet 103 is a sheet such as a transfer roller.
The data is sent to the read-ahead reading unit 30 by the transfer unit 110. Destination
The reading unit 30 emits light from the pre-reading laser light source 201.
The emitted laser light 202 is excited by the laser light 202.
Of the stimulated emission light emitted from the stimulable phosphor sheet 103
After passing through the filter 203 that cuts the wavelength range,
The light is deflected linearly by an optical deflector 204 such as a ruvanometer mirror.
And the stimulable phosphor sheet 103 via the plane reflecting mirror 205.
Incident on top. Here, the laser light source 201 is used as excitation light.
The wavelength range of the laser beam 202 is emitted by the stimulable phosphor sheet 103.
Is selected so that it does not overlap with the wavelength range of the stimulated emission
I have. On the other hand, the stimulable phosphor sheet 103 is used for a transfer roller or the like.
The sheet is transported in the direction of arrow 206 by the sheet
The scanning is performed, and as a result, all of the stimulable phosphor sheet 103 is scanned.
The laser light 202 is irradiated over the surface. Where
The light intensity of the light source 201, the beam diameter of the laser light 202, the laser
Scanning speed of light 202, transfer speed of stimulable phosphor sheet 103
Means that the energy of the pre-reading excitation light (laser light 202) is
This is the main reading performed by the main reading unit 40 described later.
Is selected to be smaller. When irradiated with the laser beam 202 as described above, the storage fluorescent
The optical body sheet 103 holds the radiation
It emits stimulating light of the amount corresponding to the energy, and this light emission
The light enters the pre-reading light guide 207. Stimulated light
Is guided through the light guide 207 of the
Received by the photodetector 208 such as a multiplier
You. The light receiving surface of the photodetector 208 has a wavelength range of photostimulated light.
That transmits only the light of the wavelength range and cuts the light in the wavelength range of the excitation light.
Filter is attached, and it can detect only stimulated emission light.
It has become so. Detected photostimulated light is stored and recorded
Converted to an electrical signal carrying the acquired image information and an amplifier
Amplified by 209. The signal output from the amplifier 209 is
Digitized by A / D converter 211, pre-read image signal
Input to the book reading control circuit 314 of the book reading reading unit 40 as Sp.
Is done. The book-reading control circuit 314 controls the pre-reading image signal Sp.
Based on the data, for example, by histogram analysis, etc.
In set value a, recording scale factor set value b, image
The gradation processing condition setting value c, which is one of the processing condition setting values, is determined.
Set. The stimulable phosphor sheet for which pre-reading has been completed as described above
The target 103 is transferred to the reading unit 40 for book reading. Book reading
The laser beam emitted from the main reading laser light source 301 in the section 40
The laser beam 302 emits a stimulable fluorescent light by excitation of the laser beam 302.
The wavelength region of photostimulated light emitted from the optical sheet 103
After passing through the cut filter 303, the beam
The size of the beam diameter is strictly adjusted by the Pander 304
And directly by an optical deflector 305 such as a galvanometer mirror.
Linearly deflected and stimulable phosphor via a plane reflector 306
The light is incident on the sheet 103. Optical deflector 305 and flat reflector 306
An fθ lens 307 is disposed between the
The beam diameter of the laser beam 302 that scans the beam 103 becomes uniform
It has been like that. On the other hand, the stimulable phosphor sheet 103 is moved.
The direction of arrow 308 by sheet transport means 320 such as a feed roller
Is transferred to the sub-scan, and as a result, the stimulable phosphor
The entire surface of the sheet 103 is irradiated with laser light. This
When the laser light 302 is irradiated as shown in FIG.
Port 103 is the radiation energy stored and recorded in it
Emits stimulating luminescence light in a quantity corresponding to the
The light enters the light guide 309 only. Inside the book reading light guide 309
The stimulated emission light guided while repeating total internal reflection is the emission surface
From the photodetector 31 such as a photomultiplier
0 is received. The light-receiving surface of the photodetector 310
A filter that selectively transmits only the wavelength range of the emitted light is attached.
So that the photodetector 310 detects only photostimulated light.
It has become. Radiation image recorded on the stimulable phosphor sheet 103
Of photodetector 310 that photoelectrically detected stimulated emission light
The force is the read gain setting value a determined by the control circuit 314.
By the amplifier 311 whose reading gain is set based on
The signal is amplified to an appropriate level. Amplified telecommunications
The signal is input to the A / D converter 312 and the recording scale factor
Recording scale suitable for signal fluctuation range based on set value b
A signal processing circuit that is converted to a digital signal by a factor
313 is entered. The above digital signal, that is, the main reading image
The image signal is applied to the signal processing circuit 313 for observation and interpretation.
The gradation processing conditions are set so that a radiation image with excellent
The gradation processing (signal processing) is performed based on the constant value c and output.
You. The read image signal (main reading) output from the signal processing circuit 313
Image signal) So is input to the optical modulator 401 of the image reproducing unit 50
Is done. In the image reproducing unit 50, the recording laser light
The laser light 403 from the source 402 is
On the basis of the actual read image signal So input from the signal processing circuit 313.
Is modulated and deflected by the scanning mirror 404.
Scanning is performed on a photosensitive material 405 such as a film. And photosensitive material
The material 405 is in a direction orthogonal to the above scanning direction (arrow 406 direction)
Is transferred in synchronization with the scanning, and the book is placed on the photosensitive material 405.
A radiation image based on the read image signal So is output. radiation
As a method of reproducing a line image, in addition to such a method,
Adopt various methods such as the above CRT display
Can be. Next, even if the photographing position of the subject 101 changes, the reproduced image
In, the density of the region of interest can be made uniform,
The features of the method of the present invention will be described. A / D converter 211
The pre-read image signal Sp output from the
Control circuit 314 and the density correction control circuit.
Input to the road 500. FIG. 4 shows this density correction control circuit 500.
FIG. 4 is referred to in detail below.
I will explain. Signal extraction unit 501 of density correction control circuit 500
From the input pre-read image signal Sp
Of the image signal relating to the partial area P at a predetermined position in the
Extract only This partial area P is set by the area setting unit 502.
Radiographic image of the thoracic vertebra as described above
When reading information, as shown in Figures 2A and 2B,
5 × 5cm, 7 × 7cm
Set to the size. Hereafter, a place corresponding to this image of the thoracic spine
An example will be described. Extraction of only partial area P
The read-ahead image signal Sp ′ is input to the analysis unit 503.
The analyzing unit 503 examines the extracted pre-read image signal Sp ′.
Create a stogram and find its average value Save. Partial territory
This average value, which is a representative value indicating the amount of stimulated emission from region P
Save is sent to the arithmetic unit 504, and the
Is the total pre-read image signal S obtained by the main read control circuit 314.
The maximum value Smax and the minimum value Smin of p are input. Arithmetic unit 5
In 04, a discrimination value Q of Q = (Save−Smin) / (Smax−Smin) is obtained from the three values thus input. This discrimination value Q is input to the comparison unit 505.
The comparison unit 505 receives the input from the reference value setting unit 506.
The reference value R is compared with the discrimination value Q, and Q exceeds the reference value R.
The correction signal T to the read gain correction circuit 507
You. The correction circuit 507 receives the correction signal T and
The read gay determined by the read control circuit 314 as described above.
The setting value a is corrected so as to lower the reading gain. Destination
As described in, the front and side images of the thoracic spine K
Is compared, the value of the discrimination value Q becomes relatively large.
Is the side shot image, and the image reading conditions and
If the image processing conditions are constant, the playback image
And the density of the thoracic spine K is
Higher. So, make the above correction
If the read gain is lowered by scanning, the pre-read image signal So
Regenerating radiation that becomes low level and is reproduced on the photosensitive material 405
The density of the image becomes lower overall. As a result, this thoracic side
The density of the portion of the thoracic spine K in the reproduced image of the surface
Of the thoracic vertebra in the reproduced image of FIG. What
The appropriate correction amount for the reading gain is determined based on experiments or experience.
Can be determined based on In the above embodiment, the main reading is performed for the front photographed image.
Reading with the read gain determined by the control circuit 314
And lower the reading gain when reading the side shot image.
It has been corrected, but on the contrary,
Is the same as the reading gain determined by the main reading control circuit 314.
Scanning is performed, and the reading gain is set when reading the frontal shot image.
May be corrected higher. In the above embodiment,
Corrects the reading gain determined by the main reading control circuit 314.
The main reading control circuit 314
The read gain setting value a determined by
You may make it increase or decrease according to it. And of the playback image
To adjust the density, change the reading gain as described above.
In addition, the recording scale factor in the A / D converter 312
Condition, and the gradation processing in the signal processing circuit 313.
May be changed. How to adjust these concentrations
The law may be used concurrently. Note that the gradation processing condition is usually determined by a non-linear gradation curve.
And determined by the main reading control circuit 314, for example.
When the corrected gradation processing condition is corrected by the correction signal T
In this case, the gradation curve is shifted up, down, left and right according to the correction signal T.
Or rotate it around a predetermined position on the gradation curve.
To make the density of the region of interest in the reproduced image uniform.
Just correct it. The smell of the front and side images of the thoracic spine
In this example, the density of the thoracic spine, which is the region of interest, is
As described above, the method of the present invention is applicable to other parts such as the lumbar spine.
Stimulable phosphor sheet on which is recorded, and front and oblique etc.
Accumulation of subjects recorded in other different shooting positions
The same applies when reading radiation image information from a phosphor sheet.
Applicable to That is, images with different photographing positions
In the case of the above, usually, the aforementioned discrimination value Q is clear in each case.
Since there is a clearly different partial region P,
The position and size of the partial region P and the reference value R are appropriately set.
Just set it. The location and size of the subregion, and
The reference value R is an imaging part and an imaging position of an image to be read.
Can be set manually depending on
This information is input to the reader as a shooting menu.
In this case, based on the input information,
Automatic setting by 502 and reference value setting unit 506
it can. In addition, it is used to indirectly determine the shooting position.
The discrimination value to be extracted is, in addition to the value of Q = (Save−Smin) / (Smax−Smin) described above, for example, the value of (Smax−Save) / (Smax−Smin), or extracted in these formulas instead of Save. Look ahead
The value to which the maximum or minimum value of the image signal Sp 'is applied is
Available. Further, the apparatus shown in FIG.
A reading system for reading is separately provided.
As shown in -67242, the reading system for book reading and the reading ahead
Transfers the sheet when the pre-reading is completed, sharing the reading system
Return the stimulable phosphor sheet to the reading system by
At the time of pre-reading by the excitation light energy adjusting means.
The excitation light energy is smaller than that in the main reading.
The method of the present invention may be adapted to such an apparatus.
It is suitable even when collecting radiation image information by
Is available. Further, in the above embodiment, one stimulable phosphor sheet is
We dealt with the case where there is one image.
Divide the sheet into two or more sections and take images for each section
The present invention is applied to each division in the case of divided shooting
Just do it. Further, in the radiation image information recording / reproducing system,
Determines the image signal for condition determination by pre-reading, and
No. based on the result of determination of line symmetry
Although pre-reading conditions have been determined,
In a system that does not know the actual read image signal for condition determination
May be used as the image signal. In this case,
The image signal is temporarily stored in a suitable storage means, and
Based on the actual read image signal of
Image processing conditions based on the determined results of line symmetry
And then read the main-read image signal from the storage means.
The image processing conditions
May be applied in accordance with the above. As described in detail above, the radiation image information reading of the present invention
According to the method, even if the subject's
The density of the region of interest in the image can be made uniform,
It is possible to greatly improve the diagnostic performance of radiographic images.
You. The present invention provides various modifications without departing from the scope of the invention.
Further embodiments are possible and are limited to the embodiments described above.
Not something.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing an example of a radiation image information recording / reproducing system for reading radiation image information according to an embodiment of the present invention. FIGS. FIGS. 3A and 3B are schematic diagrams showing examples of different radiation images, FIGS. 3A and 3B are graphs showing an example of a histogram of a read image signal from a stimulable phosphor sheet photographed by changing the photographing position of a subject, FIGS. FIG. 4 is a block diagram showing a part of the apparatus shown in FIG. 1 in detail. Reference numeral 20: radiation image capturing unit, 30: read-ahead read unit 40: read-ahead read unit, 100: radiation source 101: subject, 102: radiation 103: stimulable phosphor sheet 201: read-ahead Laser light source 202: pre-reading laser beam 204: pre-reading light deflector 208: pre-reading light detector 210: pre-reading sheet transfer means 301: main reading laser light source 302: main reading laser beam 305 Book reading optical deflector 310 ... Book reading photodetector, 311 ... Amplifier 312 ... A / D converter, 313 ... Signal processing circuit 314 ... Control circuit 320 ... Book reading sheet transfer means 500 ... Density Correction control circuit 507: Read gain correction circuit a: Read gain set value b: Recording scale factor set value c: Image processing condition set value, Q: Discrimination value R: Reference value, Sp: Pre-read image Signal Sp ': extracted pre-read image signal So: main read image signal Smax: pre-read image Signal maximum value Smin: minimum value of pre-read image signal Save: average value T of extracted pre-read image signal T: correction signal

Claims (1)

(57) [Claims] The main reading is performed by reading the image signal for reproducing the visible image from the recording medium on which the radiation image information is recorded, and the reading conditions at the time of performing the main reading and / or the main reading image signal read by the main reading are image-processed. A radiographic image information reading method, wherein the image processing conditions at the time are determined based on image signals for condition determination obtained by reading image information recorded on the recording medium. Extracting an image signal relating to a partial area at a predetermined position in the recording medium, obtaining a representative value of the image signal relating to the partial area, and indicating a relationship between a characteristic value of the image signal for determining the condition and the representative value. A radiation image, wherein a predetermined discrimination value is obtained, and the reading condition and / or the image processing condition are determined based on the discrimination value. Distribution reading method. 2. The representative value is an average value Save of the image signal for condition determination regarding the partial area, the characteristic value is a maximum value Smax and a minimum value Smin of the image signal for condition determination, and the determination value is (Save 2. The radiation image information reading method according to claim 1, wherein the value is: -Smin) / (Smax-Smin). 3. The representative value is an average value Save of the image signal for condition determination regarding the partial area, the characteristic value is a maximum value Smax and a minimum value Smin of the image signal for condition determination, and the determination value is (Smax 2. The radiation image information reading method according to claim 1, wherein the value is: -Save) / (Smax-Smin).