JP3030556B2 - Radiation image information processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention irradiates excitation light to a stimulable phosphor sheet on which radiographic image information is stored and recorded, thereby stimulating luminescence emitted from the sheet. The present invention relates to a method for converting a read image signal obtained by photoelectrically detecting light to improve diagnostic suitability.

(Prior art) Radiation (X-ray, α-ray, β-ray, γ-ray,
(Electron beam, ultraviolet rays, etc.), a part of this radiation energy is accumulated in the phosphor, and when this phosphor is irradiated with excitation light such as visible light, the phosphor is stimulated according to the accumulated energy. It is known to emit light, and a phosphor exhibiting such properties is called a stimulable phosphor (stimulable phosphor).

Using this stimulable phosphor, radiation image information of a subject such as a human body is temporarily recorded on the stimulable phosphor in a sheet form, and the stimulable phosphor sheet is scanned with excitation light such as a laser beam to excite. Emitting light is generated, and the obtained stimulating emitted light is photoelectrically read by a photomultiplier tube (photomultiplier) or the like to obtain an image signal. Based on the image signal, a radiation image of the subject is converted to a photographic material or the like. The present applicant has already proposed a radiation image information recording / reproducing system for outputting a recording material, a CRT or the like as a visible image. (Japanese Patent Laid-Open No. 55-124
29, 56-11395, 55-163472, 56-104645,
No. 55-116340. In the above system, in order to eliminate the influence of the fluctuation of the imaging conditions or to obtain a radiographic image having excellent suitability for observation and interpretation, the recording state of the radiographic image information stored and stored in the stimulable phosphor sheet, or the chest, A recording pattern (hereinafter, collectively referred to as “accumulated recording information”) determined by a part of a subject such as an abdomen and an imaging method such as simple imaging and contrast imaging is visible for observation and interpretation. Grasping prior to image output, adjusting the reading gain to an appropriate value based on the grabbed accumulated recording information, and determining the recording scale factor so that the resolution is optimized according to the contrast of the recording pattern If image processing such as gradation processing is further performed on the read image signal, it is desirable to set the image processing conditions optimally.

A method disclosed in Japanese Patent Application Laid-Open No. 58-67240 is known as a method for grasping the storage record information of a radiation image prior to outputting a visible image. In this method, prior to the main reading, a lower level of excitation light than the excitation light to be irradiated is used in a reading operation for obtaining a visible image for observation reading (hereinafter referred to as “main reading”). A reading operation (hereinafter, referred to as “pre-reading”) for grasping the accumulation record information of the radiation image accumulated and recorded on the stimulable phosphor sheet is performed, thereby grasping the outline of the accumulation record of the radiation image. is there.

However, when the prefetching described above is performed, the time required for the reading process is prolonged, and the mechanism of the apparatus becomes complicated. Therefore, recently, a radiographic image having excellent suitability for observation and interpretation has been obtained without performing the prefetching. Methods are also being considered.
In this method, a reading process for obtaining a visible image for observation reading is performed by sufficiently widening a stimulating emission light detection range, and an optimum reading gain in this case is obtained from a reading image signal obtained thereby, and The read image signal is converted so as to be equivalent to an image signal obtained under the read gain. The optimal reading gain Sk in this case is
For example, image signals Smin to Smax in a range provided for image reproduction
Is a reading gain corresponding to the median of image signals Qmin to Qmax in a predetermined range input to the image reproducing apparatus, and is obtained as a function of the characteristic value Smean of the image signal. At this time, the input signal level corresponding to the center value Qcenter of the output image signal range (511 in the case of 0 to 1023) is Sk. For example, the histogram of the read image signal is shown by A in FIG. 3, and the image signals Smin to Sm
When the median value of ax is Smean, if the image signal is recorded as the image signals Qmin to Qmax with the recording scale factor Gp (this is the slope of the conversion line H in FIG. 3), the image signal histogram becomes A ′. What is necessary is just to convert the read image signals Smin to Smax so as to be as shown.

At this time, the recording scale factor Gp is, for example, Etc.

The above-mentioned recording scale factor Gp that determines the latitude of the reproduced image is also determined based on the accumulated recording information grasped by this pre-reading when performing the pre-reading described above. However, when the conversion processing for reading gain correction is performed as described above, the conversion processing for determining the latitude can be executed at the same time. The characteristic value Gp for determining the latitude and the characteristic value Sk for the conversion processing for reading gain correction described above are basically obtained if the minimum value Smin and the maximum value Smax of the image signal to be used for image reproduction are known. Therefore, for example, if Smin and Smax are obtained for all read image signals obtained by broadening the photostimulated emission light detection level as described above,
The characteristic values Sk and Gp are obtained. In this way, the characteristic value Sk,
Once Gp is determined, based on these values, for example, Q = Gp (S−Sk) + Qcenter (1) Qcenter: center value of output image signal range (511 in case of 0 to 1023) By performing the conversion process, the above-described conversion process for correcting the reading gain and the conversion process for determining the latitude can be performed simultaneously.

(Problems to be Solved by the Invention) An object of the present invention is to provide a radiation image information processing method capable of efficiently performing the above-described conversion processing after performing a radiation image information reading processing. Things.

(Means and Actions for Solving the Problems) According to the radiation image information processing method of the present invention, the reading is performed without setting the reading gain and / or the recording scale factor based on the storage record information of the stimulable phosphor sheet. After performing the processing, after digitizing the analog read image signal output from the photoelectric reading means such as the photomultiplier tube, the digital image signal has characteristics corresponding to a range of image signal values effective for diagnosis. Values, ie, the aforementioned characteristic values Sk and Gp, etc., and then a table for normalizing conversion processing of the digital image signal based on these characteristic values so as to optimize the reading gain and / or the recording scale factor. After converting the digital image signal in accordance with this table, the signal is subjected to gradation processing. It is characterized in that the image signal after was as to provide for the reproduction of radiation image information.

(Examples) Hereinafter, the present invention will be described in detail based on examples shown in the drawings.

FIG. 1 shows an example of an apparatus for reading radiation image information from a stimulable phosphor sheet, converting this information by the method of the present invention, and reproducing and recording a radiation image based on the information after the processing. . As an example, this apparatus is configured to read and reproduce and record radiation image information on the same stage. As shown in the figure, the apparatus includes a stimulable phosphor sheet supply unit 10 for detachably holding a plurality of cassettes 2 capable of accommodating a stimulable phosphor sheet 1 and an accumulator capable of accommodating a plurality of stimulable phosphor sheets. Holding section 40 for detachably holding the luminescent phosphor sheet magazine 3 and a recording sheet supply section 6 for detachably holding a recording sheet magazine 5 capable of storing a plurality of recording sheets 4.
0, an optical scanning unit 20 for reading radiation image information stored and recorded on the stimulable phosphor sheet 1 and recording the read image information on the recording sheet 3;
An erasing unit 30 for erasing image information remaining on the stimulable phosphor sheet 1 that has been read in 20 and an automatic developing machine 7 for developing the recording sheet 3 that has been recorded in the optical scanning unit 20
A tray holding section 80 for detachably holding a tray 6 capable of storing a plurality of stimulable phosphor sheets is provided. After the stimulable phosphor sheet 1 taken out of the cassette holding unit 10 is conveyed to the optical scanning unit 20 and the erasing unit 30 in this order, the first stimulable phosphor sheet to be carried into the cassette holding unit 10 again. Body sheet conveying means, second stimulable phosphor sheet conveying means for conveying the stimulable phosphor sheet 1 taken out of the magazine holding unit 40 to the optical scanning unit 20, the erasing unit 30, and the tray holding unit 80 in this order; The recording sheet 4 taken out from the recording sheet supply section 60 is fed to the optical scanning section 20 and an automatic developing machine.
70 is provided with recording sheet conveying means for conveying in this order. In addition, these three transporting means have many parts in common with each other, and here, these transporting means are collectively referred to as "sheet transporting means 50" for convenience.

In an external photographing device (not shown), the cassette 2 photographed with respect to the stimulable phosphor sheet 1 housed therein is loaded into the cassette holding unit 10. The cassette 2 is used to irradiate the stimulable phosphor sheet 1 with radiation to record (photograph) image information.
Has a light-shielding property in order to prevent it from being exposed to external light, and comprises a cassette body 2a for storing the stimulable phosphor sheet 1 and an openable and closable lid 2b. This lid 2b
Is closed when the cassette 2 is loaded into the cassette holding unit 10, but when the internal stimulable phosphor sheet 1 is taken out of the cassette holding unit 10, the air suction cup or the like is closed. As shown, the lid opening means 11 is
open. When the lid 2b is opened, the stimulable phosphor sheet take-out means 12, such as an air suction cup, enters the cassette 2 to adsorb the stimulable phosphor sheet 1, and sends it to the nearby sheet conveying means 50. The stimulable phosphor sheet 1
Is held in the cassette 2 such that the surface on the front side on which the stimulable phosphor layer is formed faces down.

Stimulable phosphor sheet 1 taken out of the cassette 2 as described above is sent to the arrow A ₁ direction by the sheet conveying means 50. In the sheet conveying means 50, there is provided a distribution plate 51 which can take a position shown by a solid line and a position shown by a broken line in the figure. When the sheet is taken out, the stimulable phosphor sheet 1 is at the position shown by the solid line in the drawing, and is allowed to be conveyed in the direction of the optical scanning section 20. The stimulable phosphor sheet 1 further includes an arrow
The light is conveyed in the directions A ₂ and A ₃ and carried into the optical scanning unit 20.

The light scanning unit 20 stores and records radiation image information on the stimulable phosphor sheet 1 and irradiates the sheet 1 with a laser beam.
Scanning is performed at 21, and the stimulated emission light emitted from the sheet 1 is photoelectrically read by photoelectric reading means 22 such as a photomultiplier to operate to obtain an electric image signal for outputting a visible image. I do. In the figure, reference numeral 23 denotes a laser light source such as a He-Ne laser, 24 denotes an optical deflector such as a galvanometer mirror, and 25 denotes a photostimulated light emitted from the stimulable phosphor sheet 1 by a light guide 22a of a photoelectric reading means. The guide 22a is a reflection mirror that reflects the photostimulated light toward the photodetector 22b such as a photomultiplier while totally reflecting the photostimulated light. In the figure, reference numeral 26 denotes an optical modulator such as an AOM, which stops operating when the laser beam 21 is scanned on the stimulable phosphor sheet 1.

Stimulable phosphor sheet 1 is transported to the optical scanning unit 20 is conveyed in the arrow A ₄ direction by the stimulable phosphor sheet conveyance means 50, therewith the laser beam 21 is deflected in the conveying direction substantially perpendicular Scanned. As a result, the entire surface of the stimulable phosphor sheet 1 is two-dimensionally scanned, and stimulated emission light corresponding to the accumulated recording information is emitted. The stimulated emission light is detected by the light detector 22b via the light guide 22a. The photostimulated light is converted into an electric signal by the photodetector 22b, and the obtained electric signal (read image signal) is sent to the image information processing circuit 27, where it is amplified and image-processed (this will be described in detail later). Receive.

Each element arranged in the light scanning unit 20 is not limited to the above, for example, by detecting the photostimulated emission light by a long photomultiplier having an elongated light receiving surface extending along the main scanning line (See JP-A-62-16666).

In this embodiment, since the pre-reading as described above is not performed, the reading process is performed by setting the photostimulated emission light detection range of the photodetector 22b to be sufficiently wide, for example, about four digits.

The stimulable phosphor sheet 1 from which image information has been read in the optical scanning unit 20 as described above is placed in the sheet conveying means 50.
Is conveyed in the directions of arrows A ₆ and A ₇ toward the erasing section 30.
Although a distribution plate 52 is provided between the light scanning unit 20 and the erasing unit 30, when the stimulable phosphor sheet 1 is transported, the distribution plate 52 is indicated by a solid line in the figure. In the position, the stimulable phosphor sheet 1 is guided to the erasing unit 30.

The erasing section 30 is for erasing the radiation image information remaining on the stimulable phosphor sheet 1 after completion of the reading (discharging the radiation energy remaining in the stimulable phosphor). That is, part of the radiation image information accumulated and recorded on the stimulable phosphor sheet 1 remains after being read, and the erasing of the remaining image information is performed by the erasing unit 30 in order to reuse the sheet 1. Done. The erasing section 30 in this embodiment, a fluorescent lamp, a tungsten lamp, sodium lamp, xenon lamp, is provided erasing light source 31 such as iodine lamps, the stimulable phosphor sheet 1 while being conveyed in the arrow A ₈ direction thereof Of light from the erasing light source 31 of FIG. Thereby, the remaining radiation energy on the stimulable phosphor sheet 1 is released. This eraser
The erasing method in 30 may be any known method, and erasing may be performed by heating or by using both light irradiation and heating.

The stimulable phosphor sheet 1 that has been subjected to the erasing process in the erasing section 30 is guided in advance by the distribution plates 53 and 54 arranged at positions shown by solid lines in the figure, and is conveyed in the directions of arrows A ₉ and A ₁₀ . rear,
It is conveyed backward to the arrow A ₁₁ direction by a switchback. Prior to the switchback of the stimulable phosphor sheet 1, the distribution plate 54 has been moved to the position shown by the broken line in the figure.
It is conveyed in an arrow A ₁₂ to A ₁₄ direction by 50 cassette holder
Sent to 10. Before the stimulable phosphor sheet 1 is carried into the cassette holding unit 10, the distribution plate 51 moves to a position shown by a broken line in the drawing, and the stimulable phosphor sheet 1 is guided by the distribution plate 51. which is conveyed in the arrow a ₁₅ direction is carried into the empty cassette 2 within the cassette holding portion 10. The stimulable phosphor sheet 1 housed in the cassette 2 in this way can be taken out of the apparatus while being housed in the cassette, carried to an external photographing apparatus, and used for new photographing.

On the other hand, when the stimulable phosphor sheet 1 taken out of the cassette 2 is carried out of the optical scanning section 20, one recording sheet 4 is taken out from the magazine 5 in the recording sheet supply section 60 by the suction means 61, and the vicinity thereof is taken out. To the sheet conveying means 50. The sheet conveying means 50 receives the recording sheet 4, conveys it in the directions of arrows B ₁ , B ₂ , B ₃ and sends it to the optical scanning section 20. Recording sheet 4 is conveyed through the optical scanning unit 20 in the arrow B ₄ direction, and the Sai該sheet 4, previously recorded image information read from the stimulable phosphor sheet 1 is carried out. That is, the light scanning unit 20
When the recording sheet 4 is conveyed in the step (a), the optical modulator 26 according to the image signal output from the image information processing circuit 27 described above (these correspond to the read image signal obtained in the above-described reading process). Is driven, and the operation of the photodetector 22b is stopped. The recording sheet 4 is scanned by a laser beam 21 which is recording light that has been modulated by the optical modulator 26 and then deflected by the optical deflector 24, whereby the recording sheet 4
Then, the image information recorded on the stimulable phosphor sheet 1 is reproduced and recorded as a photographic latent image.

The recording sheet 4 on which the image information is reproduced and recorded in the optical scanning unit 20 is conveyed in the directions of arrows B ₅ and B ₆ by the sheet conveying means 50 and sent to the automatic developing machine 70. At that time, the distribution plate
Reference numeral 52 moves to the position shown by the broken line in the figure to guide the recording sheet 4 to the automatic developing machine 70. As shown, the apparatus includes a cassette holding unit 10, a magazine holding unit 40, a recording sheet supply unit 60,
The optical scanning unit 20, the erasing unit 30, and the sheet conveying means 50 are housed in the same housing 7, and the automatic developing machine 70 is integrally connected to the side of the housing. This automatic processor
At 70, the recording sheet 3 is sent to a developing zone 71, a fixing zone 72, a rinsing zone 73, and a drying zone 74 in that order, subjected to a developing process, and stored in a tray 75.

Note that the present apparatus is provided with the magazine holding unit 40 as described above, and is also capable of executing a reading process on the stimulable phosphor sheet 1 stored in the magazine 3. That is, the magazine holding section 40 is provided with a sheet take-out means 41 such as an air suction cup, and the stimulable phosphor sheets 1 taken out one by one from the magazine 3 by the take-out means 41.
Is fed to the sheet conveying means 50 in the vicinity, after the stimulable phosphor sheet 1 is conveyed to the arrow C ₁ direction, likewise an arrow C ₂ -C and the stimulable phosphor sheet taken out from the cassette 2 described above _The reading unit 20 and the erasing unit 30 are transported in _seven directions.
To be read and erased. The stimulable phosphor sheet 1 is further conveyed in the directions of arrows C ₈ and C ₉ , then switched back in the direction of arrow C ₁₀ , guided by the distribution plate 53 moved to the position shown by the broken line in FIG. It is carried into the tray 6 in the section 80.

Next, image processing will be described. FIG. 2 shows a schematic configuration of an image processing circuit in the above-described image information processing circuit 27, which will be described below with reference to FIG. As shown, a buffer memory 81, an input line memory 82, and a Sk / Gp conversion microprocessor 83 are connected to the bus 99A, and an original data frame memory 84 is connected to the Sk / Gp conversion microprocessor 83. Have been. A bus 99B communicating with the bus 99A via the interface 85 has a frame memory 86 for blur mask data, a buffer memory 87 for enlargement, a format for storing a reproduced image format and ID information of a subject, and a format for ID. The memory 88 and the output line memory 89 are connected. Also, an upper MPU (microprocessor unit) interface 90 and a microprocessor 92 are connected to the bus 99A. A processor memory 93 for operating the microprocessor 92 and the interface 90 are connected to the upper
Connected to bus 99C. On the other hand, the bus 99B has an upper MPU
An interface 97 and a microprocessor 94 are connected, and a processor memory 96 for operating the microprocessor 94 and the interface 97 are connected to an upper MPU bus 99C. Also microprocessors 92, 9
4 has a high-speed RAM that temporarily stores the data being processed
91 and 95 are connected. The microprocessor 92 is a high-level MP that controls the radiation image information reading process and the reproduction recording process.
Bus 99C and interface by U (not shown)
The operation is controlled via 90. Microprocessor as well
The operation of 94 is controlled by the host MPU via the bus 99C and the interface 97.

As described above, when the process of reading the radiation image information from the stimulable phosphor sheet 1 is performed in the optical scanning unit 20, the analog read image signal S obtained by this reading process is converted to an A / D converter. After being digitized by 79, it is input to the input line memory 82,
From 82, a read image signal Sd corresponding to one main scanning line is output. The microprocessor 92 calculates the above-described characteristic values Sk and Gp from the read image signal Sd input for each line according to a predetermined program stored in the processor memory 93. A process of creating a conversion table based on the information and an RI removal process are performed. This RI removal processing is performed, for example, by the applicant of the present application.
Nos. 62-92761, 62-92762 and the like, and by receiving this processing, from the read image signal Sd,
A noise component that causes black dots in the reproduced image is removed. The digital read image signal Sd on which the RI removal processing has been performed is temporarily stored in the buffer memory 81, and finally a signal for one image is stored in the frame memory 84 as original image data Sorg.

The table created by the microprocessor 92 is for converting image data in accordance with the above-described formula (1) as an example based on the characteristic values Sk and Gp obtained as described above. This is as shown by the straight line H in FIG. This table is digitally developed and stored in the buffer memory 81.

On the other hand, the microprocessor 94
Performs the process of obtaining the blur mask data Sus while receiving the read image signal Sd for each line. The blur mask data Sus is, for example, an average value of image signals of pixels within the mask size. In this case, if the mask size is N × N, Sus = ΣS / N ² . The blur mask data Sus thus obtained one by one is stored in the frame memory 86 for blur mask data.

The processing for obtaining the characteristic values Sk and Gp described above, the processing for creating the conversion table, the RI removal processing, and the blur mask calculation processing are performed during the period from the execution of the reading processing to the start of the reproduction and recording processing of the radiation image information. Done.

Next, when performing the reproduction / recording processing of the radiation image information in the optical scanning unit 20 as described above, the Sk / Gp conversion microprocessor 83 transmits the original image data Sorg stored in the frame memories 84 and 86, Mask data
Sus is read out, and these data Sorg and Sus are subjected to the conversion processing shown in the above-described equation (1) in accordance with the conversion table stored in the buffer memory 81. That is, the original image data Sorg is converted into data Qorg such that Qorg = Gp (Sorg−Sk) + Qcenter. Thus, the characteristic value Sk,
By performing the conversion process based on Gp, the converted data Qo
rg is such that the overall level is suitable for the density range of the reproduced image, and the latitude is also optimized. In association with this conversion, the blur mask data Sus is also converted into data Qus of Qus = Gp (Sus−Sk) + Qcenter.

The above conversion table is used for data Sorg or Sus.
Is input to the address as it is, whereby the converted value is directly output. By doing so, the time required for this conversion processing can be reduced.

The image data Qorg and the blur mask data Qus obtained by the above-described conversion are sequentially Sk / Gp
Output from the conversion microprocessor 83. The microprocessor 92 receives these image data Qorg and blur mask data Qus, and performs frequency processing and gradation processing on the image data Qorg. This frequency processing is described in, for example, JP-A-56-138735.
In this case, a spatial emphasis coefficient of β or more is emphasized by performing a conversion of Qorg + β (Qorg−Qus) with β as a frequency emphasis coefficient. The microprocessor 92 performs the frequency processing and the gradation processing as one processing. That is, if the gradation correction coefficient is γ, the image data Qo
rg is converted into image data Qout such that Qout = γ {Qorg + β (Qorg−Qus)}. By performing the above-described frequency processing, it is possible to obtain a visually reproducible reproduced image. The above-mentioned gradation processing is disclosed in, for example, JP-A-56-11034. By performing this processing, the gradation of a reproduced image can be optimized.

The image data Qout subjected to the above processing is output from the image information processing circuit 27 while being temporarily stored in the output line memory 89 for one line at a time, and is used to drive and control the optical modulator 26 of the optical scanning unit 20. Offered. Thus, the optical modulator 26
As described above, the laser beam 21 modulated based on the image data Qout is scanned on the recording sheet 4 as described above, so that the radiation image carried by the image data Qout is reproduced and recorded on the recording sheet 4.

The density resolution of a radiographic image reproduced and recorded based on the image data Qout is 10 bits (= 1024
Level) or higher. When the density resolution is 10 bits, it is desirable that the image data Qorg and the blur mask data Qus have a resolution of 11 bits or more at the stage where the frequency processing and the gradation processing are performed. By doing so, it is possible to prevent a density step from appearing in a reconstructed radiation image (particularly in the case of a tomographic image of a human body) due to an arithmetical loss in frequency processing and gradation processing.

The image data Qout is subjected to enlargement processing by the microprocessor 94 as necessary, and then sent to the output line memory 89. This enlargement process is to extend the data Qout so to speak, by appropriately interpolating the image data Qout while temporarily storing the data in the buffer memory 87. By reproducing, an enlarged image can be reproduced. Conversely, a reduction process can be performed by appropriately thinning out the image data Qout.

(Effects of the Invention) As described above in detail, in the method of the present invention, after a read image signal is digitized, a characteristic value for extracting only a component effective for diagnosis from the digital image signal is obtained. Since a table for normalizing conversion processing of the image signal based on the value so as to optimize the reading gain and / or the recording scale factor is created, and the digital image signal is converted by the table, This conversion process can be performed efficiently, and the radiation image can be reproduced within a short time after the reading process of the radiation image information.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an example of a radiation image information reading / reproducing apparatus for performing conversion processing of radiation image information by the method of the present invention, and FIG. 2 is a schematic configuration of a circuit for performing image processing of the apparatus of FIG. FIG. 3 is an explanatory diagram for explaining a conversion process for reading gain correction and a conversion process for determining latitude according to the present invention. DESCRIPTION OF SYMBOLS 1 ... storable phosphor sheet 2, 2 ... cassette 3 ... storable phosphor sheet magazine 4 ... recording sheet 5, 5 ... recording sheet magazine 6 ... tray, 7 ... housing 10 ... Holder 20, Optical scanning unit 30, Erase unit 40, Magazine holder 50 Sheet transport means 60 Recording sheet supply unit 70 Automatic developing machine 79 A / D converter 80: tray holding unit, 81: buffer memory 82: input line memory 83: microprocessor for Sk / Gp conversion 84: frame memory for original data 86 ... frame memory for blur mask data 89: output line Memory 92, 94 ... Microprocessor

Claims (1)

(57) [Claims] 1. A stimulable phosphor sheet on which radiation image information is stored and recorded is irradiated with excitation light, and stimulated emission light emitted from a portion of the stimulable phosphor sheet irradiated with the excitation light is emitted. A radiation image information reading / reproducing method for performing a reading process for obtaining an analog read image signal carrying the radiation image information by photoelectrically detecting the radiation image information, and then reproducing the radiation image information based on the read image signal. The reading process is performed without setting the reading gain and / or the recording scale factor based on the accumulated recording information of the phosphor sheet, and after digitizing the read image signal, the digital image signal is used for diagnosis. A characteristic value corresponding to the range of the image signal value is obtained, and the digital image signal is read based on the characteristic value and the reading gain and / or Create a table for normalization conversion processing so as to optimize the recording scale factor, convert the digital image signal according to this table, apply the signal to gradation processing, A radiation image information processing method, wherein an image signal is used for reproducing the radiation image information.