JPH02275432A - Method for recognizing radiograph arrangement pattern - Google Patents

Abstract

PURPOSE:To obtain the best read conditions, image processing conditions, etc., by recognizing that a radiograph recorded on a recording sheet has an arrangement pattern corresponding to its binarization mask when the extent of pattern matching is larger than a specific value. CONSTITUTION:An external frame 31 corresponds to the entirety of one stimulable phosphor sheet, an area 31a which is not hatched is an area where an image signal is all '0', and a hatched area 31b is an area where the image signal is all '1'. A obtained binary image signal and its binarization mask are compared to find an evaluated value indicating the extent of pattern matching with each binarization mask. Then, when the extent of the pattern matching of the binarization mask is larger than the specific value, it is recognized that the radiograph recorded on the recording sheet has the arrangement pattern corresponding to the binarization mask. Consequently, the arrangement pattern is recognized automatically and utilized to determine the best read conditions, image processing conditions, etc.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention scans a recording sheet such as a stimulable phosphor sheet on which one or more radiation images are recorded, and by this scanning, the radiation It relates to a radiation image reading and reproducing system that obtains an image signal carrying information representing an image and obtains a visible output image from this image signal, and more specifically, a radiation image reading and reproducing system that recognizes an arrangement pattern of radiation images recorded on the recording sheet. This invention relates to a layout pattern recognition method.

(Prior Art) It is practiced in various fields to read a recorded radiation image to obtain image data, perform appropriate image processing on this image data, and then reproduce and record the image. For example, an X-ray image is recorded using an X-ray film with a low gamma value designed to be compatible with later image processing, and the X-ray image is read from the film on which it is recorded and converted into an electrical signal. By performing image processing on this electrical signal (image data) and then reproducing it as a visible image in a copy photograph, etc., it is possible to obtain a reproduced image with good image quality performance such as contrast, sharpness, and graininess. is known (Japanese Unexamined Patent Publication No. 121043/1983).

Also, radiation (X-rays, α-rays, β-rays, γ-rays, electron beams).

When irradiated with ultraviolet rays, etc., a part of this radiation energy is accumulated, and then when excitation light, such as visible light, is irradiated, a stimulable phosphor (stimulable phosphor) that exhibits stimulated luminescence is produced according to the accumulated energy. Using this technology, radiation image information of a subject such as a human body is partially recorded on a sheet of stimulable phosphor, and this stimulable phosphor sheet is scanned with excitation light such as a laser beam to generate stimulated luminescence light. , a radiation image recording and reproducing method that photoelectrically reads the obtained stimulated luminescence light to obtain image data, and outputs a radiation image of the subject as a visible image to a recording material such as a photographic light-sensitive material, a CRT, etc. based on this image data. A system has been proposed by the applicant (Japanese Patent Laid-Open No. 55-1242
No. 9, No. 5G-11395, No. 55-163472, No. 5G-104G45, No. 55-11f3340, etc.).

This system has the practical advantage of recording images over a much wider range of radiation exposure compared to conventional radiographic systems using silver halide photography. In other words, in a stimulable phosphor, it is recognized that the amount of emitted light that is stimulated to emit light due to excitation after accumulation is proportional to the amount of radiation exposure over an extremely wide range.
Therefore, even if the amount of radiation exposure varies considerably due to various imaging conditions, the amount of stimulated luminescence emitted from the stimulable phosphor sheet can be read by the photoelectric conversion means by setting the reading gain to an appropriate value. By converting the radiation image into an electric signal and using this electric signal to output the radiation image as a visible image to a recording material such as a photographic light-sensitive material or a display device such as a CRT, a radiation image that is not affected by fluctuations in radiation exposure amount can be obtained. be able to.

In the above system, the stimulable phosphor sheet is scanned in advance with a low-level light beam in order to obtain an image signal by reading it under optimal reading conditions depending on the dose of radiation applied to the stimulable phosphor sheet. Pre-reading is performed to read the outline of the radiation image recorded on this sheet, the pre-read image signal obtained by this pre-reading is analyzed, and then the sheet is irradiated with a strong light beam and scanned to find the optimum image for this radiation image. There is a system configured to perform actual reading in which image signals are obtained by reading under reading conditions.

In addition, regardless of whether the system performs this pre-reading or the system does not perform pre-reading, the obtained pre-read image signal or image signal is analyzed to determine the optimal image processing conditions when performing image processing on the image signal. There are also systems that have This method of determining optimal image processing conditions based on image signals is not limited to systems using stimulable phosphor sheets.
For example, it is also applied to a system that obtains an image signal from a radiation image recorded on a recording sheet such as a conventional X-ray film.

(Problems to be Solved by the Invention) In the above system, for the purpose of effectively using a recording sheet such as a stimulable phosphor sheet or for comparing radiographic images taken of the same subject at different angles, , a plurality of radiation images may be photographed and recorded on one recording sheet.

When reading a recording sheet containing multiple radiographs or performing image processing, if you do not know that multiple radiographs were taken and the arrangement of the multiple radiographic images, all of the multiple radiographic images recorded on one recording sheet may be combined into one. The optimal reading conditions, image processing conditions, etc. are determined by regarding the image as a radiation image. Even if the optimal reading conditions, image processing conditions, etc. are determined by considering the images as one radiographic image, there is no significant difference in the imaging conditions or required image processing, etc. of multiple radiographic images recorded on one recording sheet. There are few problems, but if there are large differences in shooting conditions or required image processing, etc.
The reading conditions, image processing conditions, etc. determined by considering the entire radiographic image as a single radiographic image may not match the individual radiographic images, and the visible output image reproduced based on the image signal may be reproduced with inappropriate density or There is a problem in that the images are played back in a way that is difficult to see because no proper image processing is performed.

In order to avoid this problem, there is a method of inputting the number and arrangement of radiation images recorded on the recording sheet into the device using a keyboard, etc., before reading the recording sheet, but it is cumbersome and If there is a lack of manual input or input errors, the same problems as above will occur, and there may be cases where it is necessary to start over from the shooting.

In view of the above circumstances, the present invention provides a method for recognizing the arrangement pattern of radiation images (including the number of radiation images) recorded on a recording sheet from a read image signal (including a pre-read image signal). This is the purpose.

(Means for Solving the Problems) One of the radiation image arrangement pattern recognition methods of the present invention for achieving the above object is to recognize radiation images emitted from a stimulable phosphor sheet on which one or more radiation images are recorded. In a radiation image reading and reproducing system that photoelectrically reads stimulated luminescence light to obtain an image signal and obtains a visible output image from this image signal, each of type 1g1 or multiple types of arrangement patterns of radiation images recorded on the sheet is provided. In response to this, a binary mask representing this arrangement pattern as a binary signal is prepared, and prior to the main reading to read the stimulated luminescence light and obtain an image signal, the destination used for this main reading is prepared in advance. The sheet is scanned by a light beam with a lower level than the beam, and a preread image signal is obtained by performing prereading to read the outline of the radiation image recorded on this sheet, and the signal level is horizontally adjusted for the preread image signal. A histogram is obtained based on the axis, the presence or absence of a peak near the maximum luminescence amount is detected in this histogram, and when the peak is present, it is determined that there is a direct radiation part in the radiation image, and the pre-read image signal is binarized. A binarized image signal is obtained by excluding the image signal corresponding to the peak portion, and an evaluation value representing the degree of pattern matching between this binarized image signal and the binarized mask is calculated for each of the binarized masks. and the binarized image signal, and among the obtained evaluation values, the maximum evaluation value with the highest degree of pattern matching is determined, and this maximum evaluation value is set as a predetermined value representing a predetermined degree of pattern matching. The feature is that the above-mentioned arrangement pattern is recognized by comparing it with the above-mentioned arrangement pattern.

Furthermore, the radiation image arrangement pattern recognition method of the present invention is applicable not only to systems using stimulable phosphor sheets, but also to systems that read radiation images recorded on conventional X-ray films, etc. from recording sheets on which radiation images are recorded. It can also be applied to general systems that read radiographic images. It is also applicable to systems that do not read ahead. In this case, the radiographic image arrangement pattern recognition method of the present invention photoelectrically reads light carrying information representing a radiographic image obtained from a recording sheet on which one or more radiographic images are recorded to generate an image signal. In a radiographic image reading and reproducing system that obtains a visible output image from this image signal, this arrangement pattern is converted into a binary signal corresponding to each of the IFIi type or multiple types of arrangement patterns of the radiographic image recorded on the sheet. Prepare a binarization mask expressed by , obtain a histogram of the image signal with the signal level as the horizontal axis, detect the presence or absence of a peak near the maximum value in this histogram, and if the peak exists, It is determined that there is a direct radiation area in the radiation image, and the image signal is binarized to obtain a binarized image signal excluding the image signal corresponding to the peak part, and this binarized image signal and the binary image signal are An evaluation value representing the degree of pattern matching with the conversion mask is obtained for each combination of the binary mask and the binary image signal, and among the obtained evaluation values, the maximum evaluation with the highest degree of pattern matching is calculated. The arrangement pattern is recognized by determining a value and comparing this maximum evaluation value with a predetermined value representing a predetermined degree of pattern matching.

(Function) The radiographic image arrangement pattern recognition method of the present invention uses a binarized mask that represents the arrangement pattern of a radiographic image recorded on a recording sheet such as a stimulable phosphor sheet as a binary signal. The image signals obtained by reading the radiation image (including the pre-read image signal) are prepared for each of the two.
A binarized image signal is obtained by digitization, and a binarized mask with the highest degree of pattern matching with this binarized image signal is obtained as described above, and the degree of pattern matching of this binarized mask is determined. is greater than a predetermined value, the radiation image recorded on the recording sheet is recognized as having an arrangement pattern corresponding to this binarized mask, so there is no need to instruct the arrangement pattern from a keyboard etc. in advance. The device automatically recognizes the arrangement pattern, which can be useful for determining optimal reading conditions, image processing conditions, etc.

Also, if there is a direct radiation area (so-called snooker area) in the image, for example, if the subject such as an arm is in the center of the image and extends from the top edge of the screen to the bottom edge, and there are direct X-ray areas on both the left and right sides, , this direct radiation area is located 2 times on the left and right side of the image.
Since there is a risk that it may be determined that there are two divided images, the present invention recognizes the arrangement pattern while excluding this direct radiation part, so that the accuracy of pattern recognition is high.

That is, for the image signal, a histogram is obtained with the signal level as the horizontal axis, the presence or absence of a peak near the maximum value is detected in this histogram, and when the peak is present, it is determined that there is a direct radiation part in the radiation image. However, since pattern matching is performed using a signal excluding the image signal corresponding to this peak portion, highly accurate arrangement pattern recognition can be performed.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 3 is a block diagram showing an embodiment of a radiation image reading and reproducing system using the radiation image arrangement pattern recognition method of the present invention. This embodiment is a system that uses a stimulable phosphor sheet and performs pre-reading.

A stimulable phosphor sheet 1 on which one or more radiation images have been recorded is first scanned with a weak light beam.
The radiation energy is set at a predetermined position in a prefetch reading section 30 that performs prefetching by emitting only a portion of the radiation energy accumulated in the radiation energy. The stimulable phosphor sheet 1 set at a predetermined position is transported in the direction of arrow Y (sub-scanning) by a sheet transport means 3 such as an endless belt driven by a motor 2.
be done. On the other hand, a weak light beam 5 emitted from a laser light source 4 is reflected and deflected by a rotating polygon mirror 6 that is driven by a motor 13 and rotates at high speed in the direction of the arrow, passes through a focusing lens 7 such as an fθ lens, and then passes through a mirror 8 to The light beam enters the sheet 1 while changing the direction of the light beam and performs main scanning in the direction of arrow X, which is substantially perpendicular to the direction of sub-scanning (direction of arrow Y). This excitation light 5
Stimulated luminescent light 9 is emitted from the irradiated portion of the sheet 1 in an amount corresponding to the radiographic image information stored and recorded, and this stimulated luminescent light 9 is collected by a light condenser lO.
It is photoelectrically detected by a photomultiplier (photomultiplier tube) 11 as a photodetector. The light condenser 10
is made by molding a light-guiding material such as an acrylic plate, and is arranged such that the linear entrance end surface 10a extends along the main scanning line on the stimulable phosphor sheet 1, and the annular shape The light-receiving surface of the photomultiplier 11 is coupled to the output end surface 10b formed in the photomultiplier 11. The above-mentioned entrance end surface 10a
The stimulated luminescent light 9 that has entered the light collector 10 from above travels through the interior of the light collector 10 by repeating total reflection, and reaches the output end face 10b.
The photomultiplier 11 detects the amount of stimulated luminescent light 9 that is emitted from the photomultiplier 11 and carries the radiation image information.

The analog output signal S output from the photomultiplier 11 is amplified by the amplifier 1B, and digitized by the A/D converter 17 to obtain a pre-read image signal S.

In the above-mentioned pre-reading, reading conditions such as the voltage value applied to the photomultiplier 11 and the amplification factor of the amplifier IB are determined so that the radiation energy accumulated in the stimulable phosphor sheet 1 can be read over a wide range. ing.

The obtained pre-read image signal Sp is sent to the calculation unit 18, and the calculation unit I8 calculates the arrangement pattern of the radiation image recorded on the stimulable phosphor sheet 1 based on the pre-read image signal S, as described later. The reading conditions for actual reading are determined to be suitable for all one or more radiation images recorded on this sheet 1. The reading conditions for this reading are:
For example, without considering whether or not the stimulated luminescence light emitted from an area where no subject exists and is simply irradiated with scattered radiation can be read properly, the presence of the subject is determined by referring to the arrangement pattern of the radiation image. It is determined so that the stimulated luminescence light emitted from the region is properly read.

The stimulable phosphor sheet 1' for which pre-reading has been completed is set at a predetermined position in the main reading section 30', and the sheet 1' is scanned by a light beam stronger than the light beam used for the above-mentioned pre-reading to obtain an image signal. Since the configuration of the main reading reader 30' is different from the configuration of the prefetch reading unit 30, a dash is added to the number used in the prefetch reading unit 30 for the component corresponding to each component of the prefetch reading unit 30. and show
Detailed explanation will be omitted.

The calculation unit 18 determines the reading conditions for main reading based on the pre-read image signal S, for example, the photomultiplier 11'.
The voltage applied to the amplifier 1G', the amplification factor of the amplifier 1G', etc. are determined.

The analog output signal S' output from the photomultiplier 11' is amplified by the amplifier 1B', and then sent to the A/D converter 1.
The signal is digitized in step 7' to obtain an image signal S'.

This image signal S' is sent to the arithmetic unit p18', and the arithmetic unit 18' refers to the arrangement pattern recognized by the arithmetic unit 18 and the reading conditions for main reading determined by the arithmetic unit 18. Optimal image processing is performed on each of the one or more radiographic images recorded in the image. The image signal subjected to image processing by the calculation unit 18' is sent to the reproduction device 20, and a visible output image is reproduced and output.

FIGS. 1A to 1F correspond to each of the various arrangement patterns of radiation images recorded on the stimulable phosphor sheet 1 shown in FIG. It is a figure showing an example of a value conversion mask. The arrangement pattern of the radiation image recorded on the stimulable phosphor sheet 1 is shown in the above 22.
In addition to those corresponding to each value mask, only one radiation image may be recorded approximately in the middle.

The outer frame 31 in each of FIGS. 1A to 1F corresponds to one entire stimulable phosphor sheet, and the unhatched area 31a is an area where all image signals are "0". The hatched area 31b indicates an area where all image signals are '1''.
The binarization mask shown in FIG. 1F is stored in advance in the calculation unit 18 shown in FIG. 3.

The prefetch image signal S obtained in the prefetch reading unit 30 shown in FIG. 3 is sent to the calculation unit 18 and then binarized to obtain a binarized image signal. To obtain a binary image signal, a predetermined value is added to the average value, median value, and minimum value for the entire screen from a set of individual pre-read image signals S corresponding to all pixels of the stimulable phosphor sheet 1. value,
A threshold value, such as a value obtained by subtracting a predetermined value from the maximum value, is first determined, and this threshold value is compared with each pre-read image signal S. If each pre-read image signal S is equal to or greater than the threshold value, It is determined by setting it to "1" in the following cases, and "0" in the following cases.

FIG. 2 shows an example of a binary image signal obtained in this manner.

The outer frame 32 in the figure corresponds to the entire one stimulable phosphor sheet like the outer frame 31 in FIGS. 1A to 1F, and the black dots 32b
indicates that the binary image signal is "1", and the other area 32a indicates that the binary image signal is "0".

When the binarized image signal is obtained in this way, the obtained binarized image signal is compared with each of the binarized masks shown in FIGS. 1A to 1F, and each binarized image signal An evaluation value representing the degree of pattern matching is obtained.

This evaluation value is, for example, if the signals at corresponding points on the stimulable phosphor sheet in the obtained binary image signal (see Figure 2) and each binary mask are both "
The number of points that are 1'' is counted and this count value is used.Also, the number of points that are ``0'' for both may be counted and this count value may be used as the evaluation value, and both are ``1''. The evaluation value may be the sum of the number of points and the number of points where both are "0".

After the evaluation values are determined for each combination of the binary image signal and each of the binary masks, the maximum evaluation value with the highest degree of pattern matching is determined from among the evaluation values. Thereafter, this maximum evaluation value is compared with a predetermined value representing a predetermined degree of pattern matching, and if the maximum evaluation value is greater than the predetermined value, the radiation image has a binarized mask arrangement pattern corresponding to this maximum evaluation value. If it is determined that this arrangement pattern exists, it is recognized that this arrangement pattern exists, and even if the maximum evaluation value is calculated as described above, it is still smaller than the predetermined value, and the radiographic image is not the same as the binarized mask corresponding to this maximum evaluation value. When it cannot be determined that the arrangement pattern has the same arrangement pattern, the entire radiation image is recognized as one radiation image.

In the arrangement pattern recognition described above, the present invention takes into consideration the case where there is a direct X-ray section as shown in FIG. It is equipped with

In FIG. 4A, a subject 40 such as an arm is shown in the center extending from the top edge of the screen to the bottom edge, and snooker parts 42 are shown on both left and right sides of the subject 40.
An example of a radiographic image with At this time, when the above-mentioned pre-read image signal is binarized, the two patterns on the left and right become "1#" and the "0" part is recognized in the center, as shown in Figure 4B. There may be cases where it is recognized as a split pattern.

Therefore, a histogram of the pre-read image signal is obtained. In this histogram, when there is the direct X-ray section 42 as described above, a peak 50 appears near the maximum value SagaXO, as shown in FIG. This peak 5o is the maximum value 5s
Since it appears above a value Smaxl that is slightly lower (by the value The presence or absence of X-rays can be directly determined. (The threshold value Th at this time and the value of the above-mentioned X can be easily determined empirically.)
Therefore, in the present invention, a histogram with the signal level as the horizontal axis is obtained for the pre-read image signal, the presence or absence of a peak near the maximum light emission amount is detected in this histogram, and when the peak is present, the radiation image It is determined that there is a direct radiation part in the area, and the placement pattern is recognized by pattern matching using a signal excluding the image signal corresponding to this peak portion, thereby realizing highly accurate placement pattern recognition.

Here, as a specific method to "exclude", when binarizing, the part corresponding to the peak of the histogram is "0".
'', or exclude the image portion corresponding to the peak of the histogram from the comparison operation when comparing with the subsequent binarization mask.

The calculation unit 18 in FIG. 3 recognizes the arrangement pattern as described above, and in consideration of this arrangement pattern, determines the optimal reading conditions for main reading, the optimal image processing conditions in the calculation unit 18', etc. can do.

Although the above embodiment describes a system that performs pre-reading, the present invention can also be applied to a system that performs reading corresponding to the main reading in the above system from the beginning without performing pre-reading.

In this case, the reading conditions at the time of reading are the predetermined reading conditions without considering the arrangement pattern of the radiation image, and an image signal is obtained, and based on this image signal, the arrangement of the radiation image is performed as described above. The pattern is recognized, and the recognized arrangement pattern is taken into consideration when performing image processing on the image signal.

In addition to systems using stimulable phosphor sheets, systems using conventional X-ray films, etc., the present invention scans a recording sheet on which one or more radiation images are recorded with a light beam, and by this scanning, The present invention can be applied to general radiation image reading and reproducing systems in which an image signal is obtained by photoelectrically reading light carrying information representing the radiation image emitted from a recording sheet, and a visible output image is obtained from this image signal.

(Effects of the Invention) As explained in detail above, the radiation image arrangement pattern recognition method of the present invention expresses the arrangement pattern of radiation images recorded on a recording sheet such as a stimulable phosphor sheet as a binary signal. A binarization mask is prepared corresponding to each arrangement pattern, and the image signal obtained by reading the radiation image (including the pre-read image signal) is binarized to obtain a binarized image signal. A binary mask with the highest degree of pattern matching with the binary image signal is determined, and if the degree of pattern matching of this binary mask is greater than or equal to a predetermined value, the radiographic image recorded on the recording sheet is Since it is recognized that there is an arrangement pattern corresponding to the binarization mask, the arrangement pattern can be automatically recognized, which can be useful when determining optimal reading conditions, image processing conditions, etc.

Further, for the image signal, a histogram is obtained with the signal level as the horizontal axis, the presence or absence of a peak near the maximum value is detected in this histogram, and when the peak is present, it is determined that there is a direct radiation part in the radiation image. death,
Pattern matching is performed using a signal excluding the image signal corresponding to this peak portion, so even if there is a direct radiation area, there is no misrecognition of the placement pattern, and highly accurate placement pattern recognition is possible. can be done.

[Brief explanation of drawings]

1A to 1F are diagrams showing examples of various binary masks, FIG. 2 is a diagram showing an example of a binary image signal, and FIG. 3 is a radiation image arrangement pattern of the present invention. A configuration diagram showing an example of a radiation image reading and reproducing system using a recognition method, FIGS. 4A and 4B show an example of an image having a direct radiation part,
FIG. 5 is a diagram showing an example of a pattern obtained by converting the image signal into a binary value. FIG. 5 is a diagram showing a histogram of a pre-read image signal of an image having a direct radiation area. 1... Stimulable phosphor sheet 2. 13... Motor 3... Sheet conveying means 4... Laser 6... Rotating polygon mirror 9... Stimulated luminescence light lO... Concentrator l
l...Photo multiplier 1G, 1[i'...
・Amplifiers 17, 17'...A/D converter 18.1
8'... Arithmetic unit 20... Playback device 3
0...Pre-reading reading unit 30'...Main reading reading unit 31, 32...Outer frame 31a, 32a corresponding to the entire one stimulable phosphor sheet...Area where the image signal is "O" 31
b... Area 321 where the image signal is "1"
+... Point 42 where the image signal is "1"...
・Direct radiation part 50...Peak showing direct radiation part Fig. 4A Fig. 4B

Claims (2)

[Claims] (1) Radiation image reading in which an image signal is obtained by photoelectrically reading the stimulated luminescent light emitted from a stimulable phosphor sheet on which one or more radiation images are recorded, and a visible output image is obtained from this image signal. In the reproduction system, a binarized mask representing one or more types of arrangement patterns of the radiographic image recorded on the sheet, in which the arrangement pattern is expressed as a binary signal, is prepared; The radiation image is recorded on the sheet by scanning the sheet with a light beam having a lower level than the light beam used for the main reading, prior to the main reading in which the image signal is obtained by reading the stimulated luminescence light. A pre-read image signal is obtained by performing pre-reading to read an outline of the pre-read image signal, a histogram with the signal level as the horizontal axis is obtained for the pre-read image signal, and in this histogram, the presence or absence of a peak near the maximum light emission amount is detected, When the peak exists, it is determined that there is a direct radiation part in the radiation image, and the pre-read image signal is binarized to obtain a binarized image signal excluding the image signal corresponding to the peak part.
Evaluation values representing the degree of pattern matching between the digitized image signal and the binarized mask are obtained for each combination of the digitized image signal and the binarized image signal, and among the obtained evaluation values, The radiation image arrangement pattern is characterized in that the arrangement pattern is recognized by determining a maximum evaluation value with the highest degree of pattern matching, and comparing this maximum evaluation value with a predetermined value representing a predetermined degree of the pattern matching. Recognition method. (2) Obtain an image signal by photoelectrically reading the light carrying information representing the radiation image obtained from a recording sheet on which one or more radiation images are recorded, and obtain a visible output image from this image signal. In the radiation image reading and reproducing system, a binarized mask is prepared corresponding to each of one or more types of arrangement patterns of the radiation images recorded on the sheet, representing the arrangement pattern as a binary signal. Then, for the image signal, obtain a histogram with the signal level as the horizontal axis, detect the presence or absence of a peak near the maximum value in this histogram, and when the peak exists, determine that there is a direct radiation part in the radiation image. and binarize the image signal to obtain a binarized image signal excluding the image signal corresponding to the peak portion, and express the degree of pattern matching between this binarized image signal and the binarized mask. An evaluation value is obtained for each combination of each of the binarized masks and the binarized image signal, and among the obtained evaluation values, a maximum evaluation value with the highest degree of pattern matching is determined, and this maximum evaluation value is obtained. A radiation image arrangement pattern recognition method, characterized in that the arrangement pattern is recognized by comparing the arrangement pattern with a predetermined value representing a predetermined degree of the pattern matching.