JPH11284813A - Radiation image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make precise corrections by removing the influence of other subscan driving irregularity from correction data for correcting polygon irregularity by selecting the number of surfaces and read sampling pitch of a rotary polygon mirror and the driving pitch of a subscan driving means so that the spatial frequencies of the polygon irregularity and subscan driving irregularity of not match each other. SOLUTION: A correcting means 150 calculates correction data for correcting polygon irregularity due to the rotary polygon mirror by the reflecting surfaces of the rotary polygon mirror by a correction data calculating means 159 and stores the correction data in a correction data memory 160. A correcting circuit 151 corrects read image data with the correction data. The number of surfaces and read sampling pitch of the rotary polygon mirror and the driving pitch of the subscan driving means are selected so that the spatial frequency of the irregularity due to the rotation of the rotary polygon mirror and the spatial frequency of periodic irregularity due to mechanical vibration of a subscan do not match each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiographic image reading apparatus for optically reading radiographic image information, and more particularly to a technique for accurately reproducing fine density information, such as a reading apparatus using a stimulable phosphor plate. The present invention relates to a technique for correcting read image data in a certain reading device.

[0002]

2. Description of the Related Art FIG. 15 is a schematic view showing a method of recording an image (for example, a medical diagnostic image) on a stimulable phosphor plate.

[0003] X-rays emitted from an X-ray source 101 are squeezed by a stop 102 and then radiated to a subject 103. The X-rays transmitted through the subject 103 enter the stimulable phosphor plate 104, whereby a latent image of the image of the subject 103 is formed on the stimulable phosphor plate 104.

The latent image is imaged by scanning a laser beam as excitation light to excite the stimulable phosphor plate 104,
The accumulated latent image energy is emitted as fluorescent light, the fluorescent light is collected by a light collector, detected by a photodetector equipped with a photomultiplier (photomultiplier), and the obtained analog electric signal is converted to A signal. After the data is digitized by the / D conversion, the data is subjected to predetermined signal processing.

The present inventor studied a technique for correcting read image data in order to reproduce images with higher precision. As a result, the following matters became clear. As a type of correction, in addition to correction of unevenness (shading) by the light condensing system and the optical system, it is necessary to correct fading in which the light emission intensity of the phosphor is attenuated with time.

For example, when a light beam is scanned by using a polygon 135 (having a surface A to surface H as a reflecting surface) as shown in FIG. 16A, as shown in FIG. However, there is a difference in the reflectance between the surface A and the other surface (for example, the surface E). As a result, even if the same position on the stimulable phosphor plate is scanned, the case where the surface A is used is different from the case where the surface E is scanned. When used, the laser power reaching the stimulable phosphor plate is different, whereby the detected signal level and the distribution content in the plane are different. Further, the signal level also differs depending on the difference in the inclination angle of each reflecting surface. Therefore, it is necessary to perform correction in consideration of the polygon surface to be used.

Further, as shown in FIG. 16 (c), the stimulable phosphor plate 104 has two-dimensional sensitivity unevenness (or unevenness caused by X-ray unevenness), aiming at higher precision. In this case, it is necessary to correct the two-dimensional unevenness.

That is, in a radiation image reading apparatus using a stimulable phosphor plate, various image irregularities occur due to the following factors. Non-uniformity in the main scanning direction: non-uniformity in the light-collecting system, non-uniformity due to the optical system (fluctuation in power of excitation light, non-uniformity in scanning speed), non-uniformity in sensitizing phosphor plate sensitivity

Non-uniformity in the sub-scanning direction: fading of the stimulable phosphor plate, X-ray heel effect (unevenness based on characteristics), movement of the reading unit, non-uniformity of the stimulable phosphor plate sensitivity (all at the sub-scanning position) Caused).

Two-dimensional unevenness: unevenness in stimulable phosphor plate sensitivity, unevenness in X-ray illuminance. Polygon unevenness: a difference in reflectance between each reflection surface of the rotating polygon mirror, a difference in reflectance within the same plane, and unevenness due to the falling of the rotating polygon mirror.

[0011] In order to correct the various types of unevenness as described above, the following several proposals have been made. (1) Japanese Patent Application Laid-Open No. 63-153048 discloses a technique of correcting an image shot with a subject placed thereon using a solid image shot without placing the subject. In Japanese Patent Application Laid-Open No. 63-158536, correction data in the main scanning and sub-scanning directions is obtained and stored from a solid image taken without placing a subject, and the image taken with the subject placed is corrected. Techniques are disclosed.

(2) Further, in the patent application of Japanese Patent Application No. 8-267112 filed by the present applicant, the smoothing process is performed on the sub-scanning correction data to improve the position reproducibility such as polygon unevenness. The technique is disclosed, eliminating the effects of no unevenness.

[0013]

In a radiation image reading apparatus that performs main scanning by a rotating polygon mirror and sub-scanning by sub-scanning driving means, in addition to the above-described non-uniformities, generally, The present inventor has newly found that unevenness in the sub-scanning direction due to the vibration of the scanning drive means and unevenness in the sub-scanning direction due to the vibration of the stimulable phosphor plate occur.

In addition, the unevenness often has a fixed frequency, and the frequency of the unevenness may coincide with the frequency of the unevenness due to the number of rotations of the rotary polygon mirror and the number of reflection surfaces. I found it.

In such a case, the unevenness (sub-scanning drive unevenness) caused by the sub-scanning driving means is included in the unevenness (polygon unevenness) caused by the rotating polygon mirror. However, even if the frequencies of the polygon unevenness and the sub-scanning drive unevenness match, the phase does not always match for each reading. For this reason, even if these two non-uniformities are subjected to non-uniformity correction using correction data created from image data having a specific phase relationship, correct correction cannot be performed for image data having a different phase relationship. ing.

FIG. 17 is an explanatory diagram showing how this kind of problem occurs. Here, the waveform of each signal is shown in the center of the drawing, the numerical value on the horizontal axis shows the position, and the vertical axis shows the amplitude. The frequency component of each signal is shown on the right side thereof, the horizontal axis shows the spatial frequency of the signal, and the vertical axis shows the intensity.

Here, FIG. 17A shows a sub-scanning profile of an image for creating correction data, and FIG. 17B shows polygon unevenness correction data obtained by averaging for each number of rotations of the rotating polygon mirror. 17C is sub-scanning correction data obtained by correcting FIG. 17A in FIG. 17B, FIG. 17D is a sub-scanning profile of a read image, and FIG. FIG. 17 shows polygon correction data corresponding to a polygon surface.
(F) is a sub-scanning profile obtained by correcting FIG. 17 (d) in FIGS. 17 (c) and 17 (b).

FIG. 17 shows an example in which the frequencies of the polygon unevenness MP and the sub-scanning drive unevenness MB match. First, with respect to the sub-scanning profile (FIG. 17A) obtained from the correction data creation image (solid image), 10
If the surface is a polygon mirror, correction is performed on polygon unevenness correction data (FIG. 17B) obtained by averaging every ten surfaces to obtain sub-scanning correction data (FIG. 17C). In addition,
In this case, polygon unevenness correction data (FIG. 17B)
17 includes polygon unevenness MP and sub-scanning drive unevenness MB having the same frequency.
(C)) has been removed.

Then, with respect to the sub-scanning profile of the read image (FIG. 17D), the polygon correction data (FIG. 17E) corresponding to the polygon surface at the time of reading and the sub-scanning correction data (FIG. 17C) )) To obtain the sub-scanning profile (FIG. 17F) of the image after the non-uniformity correction, the phase does not always coincide with the polygonal non-uniformity and the sub-scanning non-uniformity. The component of the unevenness remains without being able to correct correctly.

In FIG. 17, the case where the fundamental frequency components of the polygon unevenness and the sub-scanning drive unevenness have been described as an example, but the fundamental wave of each unevenness and some of the higher harmonic components are also identical. In such a case, a similar problem may occur.

The present invention has been made in view of such problems, and removes the influence of other sub-scanning drive unevenness from correction data for correcting polygon unevenness, thereby facilitating accurate correction. It is an object of the present invention to provide a radiation image reading apparatus that can perform the operation.

[0022]

According to a first aspect of the present invention, there is provided a photostimulable phosphor in which a radiation image is accumulated and recorded by a light beam reflected and deflected by a rotary polygon mirror having a plurality of reflecting surfaces. The main scanning of the plate is performed in a first direction, and the scanning line of the light beam and the stimulable phosphor plate are sub-scanned by a sub-scanning driving unit in a second direction perpendicular to the first direction. Light beam on the stimulable phosphor plate
In a radiation image reading apparatus that scans two-dimensionally and obtains an image signal by detecting light generated by the two-dimensional scanning, polygon unevenness caused by the rotating polygonal mirror is corrected for each reflection surface of the rotating polygonal mirror. Correction data calculating means for calculating correction data for the correction, storage means for storing the correction data, correction means for correcting the read image data with the correction data, and spatial frequency of unevenness caused by rotation of the rotating polygon mirror Let uP be the spatial frequency of the periodic unevenness caused by the mechanical vibration of the sub-scanning uB, uP and uB
The radiation image reading apparatus is characterized in that the number of faces of the rotating polygon mirror, the reading sampling pitch, and the driving pitch of the sub-scanning driving means are selected so that the two do not coincide with each other.

In this radiation image reading apparatus, the number of faces of the rotating polygon mirror, the reading sampling pitch, and the driving of the sub-scanning driving means are set so that the spatial frequency uP of the polygon unevenness and the spatial frequency uB of the sub-scanning driving unevenness do not coincide with each other. The pitch is selected and configured.

Therefore, the effects of other sub-scanning drive unevenness can be removed from the correction data for correcting polygon unevenness, and accurate correction can be easily performed. (2) According to the second aspect of the present invention, the stimulable phosphor plate on which the radiation image is accumulated and recorded is main-scanned in the first direction by the light beam reflected and deflected by the rotating polygon mirror having a plurality of reflecting surfaces. The scanning line of the light beam and the stimulable phosphor plate are sub-scanned by a sub-scanning driving means in a second direction perpendicular to the first direction, so that the light beam is stimulable phosphor plate. In a radiation image reading apparatus which scans a plate two-dimensionally and obtains an image signal by detecting light generated by the two-dimensional scanning, polygon unevenness caused by the rotating polygon mirror is reflected on each reflection surface of the rotating polygon mirror. Correction data calculating means for calculating correction data for correcting each and every position in the main scanning direction, storage means for storing the correction data, and correction means for correcting read image data with the correction data, Assuming that the spatial frequency of the unevenness caused by the rotation of the polygonal mirror is uP and the spatial frequency of the periodic unevenness caused by the mechanical vibration of the sub-scanning is uB, the rotating polygonal surface is set so that uP and uB do not coincide with each other. A radiation image reading apparatus characterized in that the number of mirror surfaces, the reading sampling pitch, and the driving pitch of the sub-scanning driving means are selected and configured.

In this radiation image reading apparatus, the number of faces of the rotating polygon mirror, the reading sampling pitch, and the driving of the sub-scanning driving means are set so that the spatial frequency uP of the polygon unevenness and the spatial frequency uB of the sub-scanning driving unevenness do not coincide with each other. The pitch is selected and configured.

Therefore, it is possible to remove the influence of other sub-scanning drive irregularities from the correction data for correcting polygon irregularities, and to easily perform accurate correction. (3) The radiation image reading apparatus according to (1) or (2), wherein the correction data calculating means is configured to output image data obtained from a scanning line scanned by the same surface of a rotary polygon mirror. The correction data is calculated based on the average value of.

In the present invention, the correction data calculating means calculates the correction data based on the average value of the image data obtained from the scanning line scanned by the same surface of the rotary polygon mirror. Correction data for correcting the polygon unevenness due to each reflecting surface of the rotating polygon mirror or correcting data for correcting each reflecting surface of the rotating polygon mirror and each position in the main scanning direction is correctly calculated. be able to.

Then, the influence of other sub-scanning drive unevenness is removed from the correction data for correcting polygon unevenness, and accurate correction can be easily performed. (4) The invention according to claim 4 is characterized in that in the radiation image reading apparatus according to (1) or (2), the uP and the uB are configured to differ from each other by 2% or more.

According to the present invention, uP and uB are 2%
As described above, the influence of other sub-scanning drive unevenness can be effectively removed from the correction data for correcting polygon unevenness, and accurate correction can be easily performed.

(5) The radiation image reading apparatus according to (1) or (2), wherein the uP and the uB are different from each other by 5% or more. I do.

According to the present invention, uP and uB are 5%
As described above, the influence of other sub-scanning drive unevenness can be more effectively removed from the correction data for correcting polygon unevenness, and accurate correction can be easily performed.

(6) The radiation image reading apparatus according to (3), wherein the average is obtained for each reflection surface.
The radiation image reading apparatus according to claim 3, wherein, when the number of lines per surface is k, the uP and the uB are different from each other by (400 / k)% or more. is there.

In the present invention, uP and uB are mutually (4)
00 / k)% or more, it is possible to effectively remove the influence of other sub-scan drive unevenness from the correction data for correcting polygon unevenness, and to easily perform accurate correction. Can be.

(7) The radiation image reading apparatus according to (3), wherein the average is obtained for each reflection surface.
4. The radiation image reading apparatus according to claim 3, wherein the uP and the uB are different from each other by (1000 / k)% or more when the number of lines per surface is k. is there.

According to the present invention, uP and uB are mutually (1)
000 / k)% or more, it is possible to effectively remove the influence of other sub-scanning drive unevenness from the correction data for correcting polygon unevenness, and to easily perform accurate correction. Can be.

(8) The invention according to claim 8 is characterized in that:
(7) In the radiation image reading apparatus of (7), the sub-scanning driving means is driven by a ball screw, and uB = 1 / D when the pitch of the ball screw is D [mm]. .

According to the present invention, when driving in the sub-scanning direction by the ball screw, when the pitch of the ball screw is D [mm], uB is defined as 1 / D, so that correction for polygon unevenness is performed. The influence of other sub-scanning drive unevenness can be accurately and effectively removed from the data, and accurate correction can be easily performed.

(9) In each of the above claims, u
If P and uB do not match, it is assumed that not only the fundamental wave but also substantial harmonic (1, 3, 5th harmonic) components are included.

(10) In the radiation image reading apparatus of (3), when k is the number of lines per one surface averaged for each reflection surface, uP and uB are mutually (2500) / K)% or more, it is possible to effectively remove the influence of other sub-scanning drive irregularities from the correction data for correcting polygon irregularities, and to easily perform more accurate correction. it can.

[0040]

Embodiments of the present invention will be described below in detail with reference to the drawings. <Configuration of Radiation Image Reading Apparatus> FIG. 1 is a block diagram showing an embodiment of the present invention. The same components as those in FIG. 15 are denoted by the same reference numerals.

A portion surrounded by a broken line in FIG. 1 is a stimulable phosphor plate reader 120, and a mechanical configuration example of the stimulable phosphor plate reader 120 is shown in FIG. First, the stimulable phosphor plate reading unit 120 will be described.
4 is fixed to the left side wall and is used repeatedly. The reading unit 130 moves along the guide shaft 143 by driving the ball screw 142 by the sub-scanning motor 141 formed of a stepping motor or the like, and scans the scanning line (light beam) 131 in the sub-scanning direction.

The scanning in the main scanning direction is performed by the polygon scanning mechanism 132. The polygon scanning mechanism 132 includes a polygon and a mechanism for rotating the polygon. The operation of the sub-scanning motor 141 is controlled by the sub-scanning motor control mechanism 145. The fluorescent light is collected by the light collector 105 and converted into an electric signal by the photomultiplier 106.

LD1 is a laser light source, PD1 is a photo sensor, and constitutes an origin position detecting sensor. This origin position detection sensor detects the origin position of the reading unit 130 in the sub-scanning direction. Photo sensor PD1
Is input to the sub-scanning motor control mechanism 145, and the sub-scanning motor control mechanism 145 controls the stop position of the reading unit 130.

Although the reading unit 130 is moved by driving the ball screw 142 here, the stimulable phosphor plate 104 may be moved in the sub-scanning direction.

Here, the entire radiation image reading apparatus will be described with reference to FIG. In FIG. 1, 1 is an X-ray source for generating X-rays, 2 is a stop for stopping the X-rays generated from the X-ray source 101, 3 is an object receiving the X-rays narrowed by the stop 102, and 4 is The stimulable phosphor plate receives X-rays transmitted through the subject 103. A latent image is formed on the stimulable phosphor plate 104 by transmitting a subject transmitted X-ray. Reference numeral 13 denotes a laser light source that generates laser light when a latent image is read, and 132 denotes a polygon scanning unit that receives laser light from the laser light source 13 and scans the stimulable phosphor plate 104 with laser light. Mechanism.

Numeral 105 denotes a condenser for condensing the fluorescence generated from the stimulable phosphor plate 104, and numeral 106 denotes the condenser 10
5 is a photomultiplier (hereinafter abbreviated as photomultiplier) for photoelectrically converting the collected fluorescence. A power supply 107 supplies a tube voltage to the photomultiplier 106.

Reference numeral 108 denotes an amplifier for amplifying the output of the photomultiplier 106; 109, a log amplifier for logarithmically compressing and amplifying the output of the amplifier 106; 110, a filter for receiving the output of the log amplifier 109 to remove noise components; A sample and hold circuit that samples and holds the output of the filter 110, and an A / D converter 112 that converts the output (analog signal) of the sample and hold circuit 111 into a digital signal.

SW is a switch for switching between a signal path at the time of creating correction data and a signal path at the time of actual image reading, and switches the common contact to the A contact side when creating the correction data and to the B contact side when reading the image.

Reference numeral 115 denotes a frame memory for storing output data (read image data) of the A / D converter 112 and image data obtained by correcting the read image data by correction means described later. 116 is stored in the frame memory 115. A controller 117 that performs predetermined processing in response to the received data is a peripheral device (printer / autonomous machine for short) such as a printer or an automatic developing machine that outputs image data sent via the controller 116. The image data is also output to a host CPU (not shown) via the controller 116.

Reference numeral 114 denotes a timing circuit. The timing circuit 114 includes a sample / hold circuit 111, A /
A timing clock is supplied to each of the D converter 112, a correction data creating unit 152, and a correction data memory 160, which will be described later. The timing circuit 114 determines the read pixel size at the time of reading according to the radiographic image capturing conditions. For example, a predetermined 0.1 mm,
One read pixel size is selected and set from three types of read pixel sizes of 0.15 mm and 0.2 mm, and the timing is sent to the sample hold circuit 111 so that reading is performed at the set read pixel size. Supply clock.

Reference numeral 150 denotes a stimulable phosphor plate reading unit 12
This is correction means for correcting digital read image data read at 0 and converted to digital data by the A / D converter 112 with correction data based on various types of unevenness.

The correction means 150 includes a correction circuit 151 for correcting the read image data, a correction data generating means 152 for generating various correction data for correcting the read image data, and a correction data in the main scanning direction. A main-scanning correction data memory 153 storing polygon-based correction data (for each reflection surface and main-scanning direction correction data);
A polygon correction data memory 154b for storing correction data (correction data for each reflection surface) caused by the polygon;
A sub-scanning correction data memory 155 for storing correction data in the sub-scanning direction, a thinning data memory 156 for storing two-dimensional unevenness correction data for two-dimensional correction, and two-dimensional unevenness correction data by interpolating the two-dimensional unevenness correction data And an adding means 158 for reading and adding the correction data stored in each memory.
Correction data calculation means 159 for calculating correction data
And a correction data memory 160 for storing the generated correction data. Such correction means 1
50 is composed of, for example, a microprocessor and a memory.

FIG. 3 shows the spatial frequency uP of the polygon unevenness corresponding to the sampling pitch and the number of polygon faces, and the spatial frequency uB of the sub-scanning drive unevenness. Note that uP = S / P when the sampling pitch is S [mm] and the number of polygon surfaces is P, and uB = 1 / D when the pitch of the ball screw is D [mm].

Here, the number of polygon faces is 1
0, 8, 6, 4 and the sampling pitch is 0.088 to 0.6 mm, and u in that case is shown.
It shows the fundamental wave to the sixth harmonic of P. In addition, the ball screw pitch and the spatial frequency uB of the unevenness in the sub-scanning driving when a ball screw is used as the sub-scanning driving unit are also shown. Here, the fundamental wave to the fifth harmonic of uB are shown.

In the radiation image reading apparatus according to the present embodiment, the rotating polygon mirror is controlled so that the integral multiple of the spatial frequency uP of the polygon unevenness and the integer multiple of the spatial frequency uB of the sub-scanning unevenness do not coincide with each other. The number of surfaces, the reading sampling pitch, and the driving pitch of the sub-scanning driving means are selected and configured.

For example, if the sampling pitch is 0.5 mm,
Spatial frequency uP of polygon unevenness when the number of polygon faces is eight
And the spatial frequency uB of the sub-scanning drive unevenness with a drive pitch of 4 mm
Are 0.25, 0.5, 0.75, 1.00, 1.2
They are exactly the same, such as 5. Further, the spatial frequency uP of polygon unevenness when the sampling pitch is 0.6 mm and the number of polygon faces is 10, and the spatial frequency uB of sub-scanning drive unevenness with a drive pitch of 6 mm are 0.17, 0.33, 0.
5, 0.67, 0.83, etc., which are completely coincident. In addition to the above, there are cases where the fundamental wave and the harmonic wave partially match. Therefore, in order to avoid such a combination that the coincidence occurs at the spatial frequency of unevenness, the number of faces of the rotary polygon mirror, the reading sampling pitch, and the driving pitch of the sub-scanning driving means are selected and configured.

Here, polygon unevenness is shown up to the sixth harmonic, and sub-scanning drive unevenness is shown up to the fifth harmonic. However, the present invention is not limited to this example. Actually, depending on how the harmonics are generated, only the low-order one may be considered, or the higher-order one may need to be considered.

Therefore, in this embodiment, the spatial frequency uP of the polygon unevenness and the spatial frequency uB of the sub-scanning unevenness do not match each other, or the integral frequency of the spatial frequency uP of the polygonal unevenness and the sub-scanning driving. The integer multiple of the spatial frequency uB of the unevenness does not match each other,
In this case, it is sufficient to consider not only the fundamental wave but also the non-uniformity of an integral multiple of the first harmonic, the third harmonic, and the fifth harmonic, which are substantial harmonic components.

Further, when "not coincident" is described in this embodiment, it means that the spatial frequency of the peak is shifted by about 1%. <Operation of Radiation Image Reading Apparatus> The operation of the apparatus configured as described above will be described below. It is to be noted that the main purpose of the present embodiment is to remove the influence of other sub-scanning drive unevenness from the correction data for correcting polygon unevenness and to easily perform accurate correction. Therefore, obtaining each correction data and performing correction can be applied to various types other than those shown here.

Correction data creation operation: The circuit shown in the figure
The solid image without the subject is stored in the frame memory 115 with the changeover switch SW turned on to the A contact side. That is, the X-ray generated from the X-ray source 101 is the subject 1
03, and enters the stimulable phosphor plate 104 to form a latent image. When reading the latent image, the polygon scanning mechanism 132 scans the stimulable phosphor plate 104 with laser light.

At this time, the generated fluorescent light is reflected by the following light collector 10.
5 and is photoelectrically converted by the photomultiplier 106. The output signal of the photomultiplier 106 is amplified by the amplifier 8, logarithmically compressed and amplified by the log amplifier 109, and the noise component is removed by the filter 110.

The output of the filter 110 is sampled and held by the sample and hold circuit 111 according to the timing generated from the timing circuit 114. The output of the sample-and-hold circuit 111 is converted into digital data by a subsequent A / D converter 112 and stored in a predetermined position of the frame memory 115 via a changeover switch SW. The above operation is repeated as necessary in the main scanning direction and the sub-scanning direction, and the image information recorded on the entire surface of the stimulable phosphor plate 104 is converted into digital image data and stored in the frame memory 115.

Then, the correction data creating means 152
The solid image data stored in the frame memory 115 is read out to create various unevenness correction data, and the main scanning correction data memory 153 and the polygon correction data memory 1
54a, a polygon inter-plane correction data memory 154b, a sub-scanning correction data memory 155, and a thinning data memory 15
6 is stored.

The thinned data memory 156 performs a predetermined correction process on the solid image data, samples the data in accordance with a certain rule, and takes into account surrounding pixel data (thinned data) to create a two-dimensional unevenness. The correction data is stored. The interpolation data creation means 157 reads out the two-dimensional unevenness correction data stored in the thinning data memory 156, creates two-dimensional unevenness correction data by interpolation based on the data, and stores the same. At this time, the interpolation data creation unit 157 creates the two-dimensional unevenness correction data of the image data of the point that is not stored in the thinning data memory 156 by using the interpolation method.

The outputs of the main scanning correction data memory 153, polygon correction data memory 154a, polygon surface correction data memory 154b, sub-scanning correction data memory 155, and interpolation data creating means 157 are added by an adding means 158 for each pixel. . The correction data calculation means 159 calculates correction data suitable for the read pixel size, and stores it in the correction data memory 160. In this way, the correction data memory 160 stores the correction data for each read pixel.

Actual image data reading process: When the correction data is obtained by the above (1), the changeover switch SW is turned on to the B side, and the image data is read with the subject 103 arranged. The read image data is supplied from the A / D converter 112 to the correction circuit 151. The correction circuit 151 subtracts the correction data of the corresponding pixel stored in the correction data memory 160 from the read image data to obtain corrected image data. The corrected image data obtained in this manner is sequentially stored in the frame memory 115. According to the present invention, in order to separately obtain various types of unevenness, main scanning unevenness,
All of the sub-scanning unevenness, two-dimensional unevenness and polygon unevenness can be easily corrected.

Creation of Unevenness Correction Data: Next, a method of creating various types of unevenness correction data by the correction data creation means 152 will be described.

With no subject, the frame memory 11
The solid image data stored in No. 5 includes main scanning unevenness, sub-scanning unevenness, polygon unevenness, and two-dimensional unevenness. Therefore, in the present invention, these unevenness correction data are separated and extracted based on the solid image data stored in the frame memory 115.

The various data used in the calculation for obtaining the correction data used for the final unevenness correction need only be present at least at the time of the calculation. Therefore, once the calculation is completed, it is unnecessary and need not necessarily be stored.

FIG. 4 is an explanatory diagram showing an example of pixel arrangement of image data. The numbers of pixels of the image data in the main scanning direction and the sub-scanning direction are i and j, respectively, and each pixel data is represented by Xuv (u =
0,1... I-1, v = 0, 1... J-1). The main scanning direction is the x direction and the sub scanning direction is the y direction.

Here, assuming that the number of reflecting surfaces of the polygon is 10, the pixels in the sub-scanning direction are 10n, 10n + 1,..., 10n + 9 (n = 0,
1, 9) and 10 groups. That is, image data using the same reflection surface of the polygon appears every ten rows in the sub-scanning direction. Referring to FIG. 4, the pixel data of the 10nth row and the pixel data of the 10n + 10th row are obtained using the same polygon surface.
The image data Xuv in FIG. 4 represents pixel data of u columns and v rows.

<Effects of this Embodiment> As described above,
FIG. 5 shows signals generated in the radiation image reading apparatus configured so that uP and uB do not coincide with each other.
This will be described with reference to the characteristic diagram of FIG.

Here, the waveform of each signal is shown in the center of the figure, the numerical value on the horizontal axis represents the position, and the vertical axis represents the amplitude. The frequency component of each signal is shown on the right side thereof, the horizontal axis shows the spatial frequency of the signal, and the vertical axis shows the intensity.

Here, FIG. 5A shows a sub-scanning profile of an image for creating correction data, and FIG.
FIG. 5C shows polygon unevenness correction data obtained by averaging for each number of rotation planes, and FIG. 5D shows sub-scanning correction data obtained by correcting FIG. 5E is a sub-scanning profile of the read image, FIG. 5E is polygon correction data adjusted to the polygon surface at the time of reading, and FIG. 5F is a diagram in which FIG. 5D is corrected in FIGS. 5C and 5B. Sub-scanning profile.

Here, the sub-scanning profile (FIG. 5A) obtained from the correction data creating image (solid image) includes:
A polygon unevenness MP having a different frequency and a sub-scanning drive unevenness MB are superimposed on the sub-scanning unevenness.

First, with respect to the sub-scanning profile (FIG. 5 (a)) of the correction data creating image, polygon unevenness correction data (FIG. 5 (b) ) To obtain sub-scanning correction data (FIG. 5C).

In this case, since the integral multiple of the spatial frequency uP of the polygon unevenness and the integral multiple of the spatial frequency uB of the sub-scanning unevenness do not coincide with each other, the sub-scanning unevenness is canceled by the above average. The polygon unevenness correction data (FIG. 5B) includes the polygon unevenness MP.
Only those related to are extracted.

Then, with respect to the sub-scanning profile of the read image (FIG. 5D), the polygon correction data (FIG. 5E) and the sub-scanning correction data (FIG. 5C) )) To obtain a sub-scanning profile (FIG. 5F) of the image after the unevenness correction.

In this case, since the spatial frequencies of the polygon unevenness MP and the sub-scanning drive unevenness MB do not coincide with each other, it is possible to obtain them separately, so that each unevenness can be correctly corrected. Become.

Accordingly, it is possible to remove the influence of other sub-scanning drive irregularities from the correction data for correcting polygon irregularities, and to easily perform accurate correction. <Confirmation of the effects of the present embodiment> In the above embodiment, the integral multiple of the spatial frequency uP of the polygon unevenness and the integer multiple of the spatial frequency uB of the sub-scanning unevenness are not matched with each other. Each non-uniformity is defined by its center frequency. However, actually, there is a spread of the spectrum with respect to the unevenness. The energy also decreases as the order of the harmonic increases.

Therefore, some conditions are determined for the embodiment of the present invention as described below, and the effect is verified. Condition 1: An integer multiple of the spatial frequency uP of the polygon unevenness and an integer multiple of uB of the spatial frequency of the sub-scanning drive unevenness are configured such that those having frequencies close to each other differ by 2% or more in frequency ratio. . Here, 2% means the ratio of the frequencies of components having similar frequencies of the components of each unevenness.

Condition 2: Integer multiple of the spatial frequency uP of the polygon unevenness and integer multiple of uB of the spatial frequency of the sub-scanning drive unevenness are different from each other by 5% or more. Condition 3: uP and uB are configured to be different from each other by (400 / k)% or more, where k is the number of lines per one surface averaged for each reflection surface of the rotating polygon mirror.

Condition 4: uP and uB, where k is the number of lines per surface averaged for each reflection surface of the rotary polygon mirror
Are different from each other by (1000 / k)% or more.

The effect obtained by the above conditions is as follows: "how much the height of the peak caused by polygon unevenness before and after correction is obtained by obtaining the power spectrum of the profile in the sub-scanning direction".

The average number of lines (k) per surface is 200
The difference between the center frequencies of polygon unevenness and sub-scanning drive unevenness (ball screw unevenness) is 1, 2, 5, 1 respectively.
FIG. 6 shows the power spectrum before and after the correction when it is 0%.
To FIG. FIG. 10 shows the remaining ratio of polygon unevenness peaks in various combinations of the difference between the average number of lines and the peak frequency. Here, the smaller the residual ratio of the polygon irregularity peak (hereinafter, referred to as peak residual ratio), the higher the accuracy of the irregularity correction, which means that the image is preferable.

As a practical effect, image data read by irradiating radiation uniformly is subjected to unevenness correction.
A hard copy was output at an average density of 1.2 and a gamma of 3.0, and the extent to which polygon unevenness was reduced was visually evaluated.

As shown in the figure, when the average number of lines is the same, the larger the difference between the peak frequencies is, the smaller the peak remaining rate becomes. When the difference between the peak frequencies is the same, the average number of lines is reduced. It was found that the larger the number, the smaller the peak residual ratio.

If the peak residual ratio is 10% or less, the effect of unevenness correction is recognized in the visual evaluation of the hard copy. Further, if the peak residual rate is 5% or less, the level is such that polygon unevenness is hardly visually recognized. Further, when the peak remaining rate is 2% or less, noises other than polygon unevenness (such as X-ray quantum mottle and sensitivity unevenness of the stimulable phosphor plate) become dominant, so that even if the peak intensity is further improved. However, the effect cannot be visually identified.

From the results of the various combinations of the difference between the average number of lines and the peak frequency and the results of the peak remaining rate, when the average number of lines per surface is k, in order to make the peak remaining rate 10% or less, It is necessary that the peak frequencies differ by (400 / k)% or more. Further, in order to reduce the peak residual rate to 5% or less, the peak frequency must be (1000 / k)%.
It is necessary to be different.

Furthermore, in order to achieve a peak remaining rate of 2% or less with high correction accuracy so that the difference in the effect cannot be visually recognized, the peak frequency must be (2500 / k)%.
It is necessary to be different.

The practical sampling pitch of a radiation image in the medical field is 80 to 400 μm. Further, the maximum size (half cut size) of an image area generally used is about 400 mm, so that the practical number of lines is 1000 to 5000 at most. The number of lines is about 500 to 2500 for a small-sized image.

On the other hand, since k is the average number of lines per plane, data of 6 k lines is required for a six-sided polygon and 10 k lines is required for a ten-sided polygon. For example,
If the difference in peak frequency is less than 1%, the number of lines used for averaging is required to be 6000 or more in order to obtain a peak remaining rate of 5% or less, which is an effect that is practically sufficient and not sufficient, which is not practical. That is, if the difference between the peak frequencies is 2% or more, the apparatus can be designed so that the effects of the present invention can be obtained for many sampling pitches and image area sizes. If the difference between the peak frequencies is 5% or more, the apparatus can be designed so that the effects of the present invention can be obtained for all practically used sampling pitches and image area sizes. is there.

<Example of application of the present embodiment to a specific device> A specific example to which the present embodiment can be applied will be described. First, preferred specific examples of the stimulable phosphor used for the stimulable phosphor plate include the following. [1] Rb (Br _x , I _1-x ): a stimulable phosphor represented by yTl (where x is a number satisfying 0 ≦ x ≦ 1 and y is 1 × 1)
It is a number that satisfies 0 ⁻⁶ ≦ y ≦ 1 × 10 ⁻² . [2] BaF (Br _x , I _1-x ): a stimulable phosphor represented by yEu (where x is a number satisfying 0 ≦ x ≦ 1 and y is 1 × 1)
It is a number that satisfies 0 ⁻⁴ ≦ y ≦ 1 × 10 ⁻² . FIG. 11 is a schematic front sectional view of a specific example of a radiation image reading apparatus to which the present embodiment can be applied.
, A control block diagram of FIG. 13, and an operation explanatory diagram of FIG.

In this embodiment, the lateral direction of the apparatus main body 2 of the radiation image reading apparatus is called an X direction, and the depth direction of the apparatus main body 2 of the radiation image reading apparatus is called a Y direction.
Therefore, the X direction and the Y direction are two directions orthogonal to each other in a horizontal plane, and the angle between the X direction and the Y direction is a right angle.

The radiation image reading apparatus of this embodiment is
As shown in FIGS. 11 to 13, the stimulable phosphor 12 was taken out from the portable cassette 9 containing the slab-like stimulable phosphor 12 which was radiographed and recorded on the stimulable phosphor 12. This is a radiation image reading apparatus that reads a radiation image and erases the read residual image remaining on the stimulable phosphor. The apparatus main body 2 of the radiation image reading apparatus according to the present embodiment includes a plate holding unit 4, an image reading unit 5, a system control unit 6, and a power supply unit 8.

The cassette stacker 3 holds the cassette 9 accommodating the plate-shaped stimulable phosphor 12 radiographed by X-ray so that the accommodated stimulable phosphor 12 is substantially perpendicular to the X direction.
Further, a plurality of sets can be arranged side by side so that the positions in the X direction are different from each other. The cassette stacker 3 takes out the stimulable phosphor 12 from the cassette 9 set in the cassette stacker 3 or stores the stimulable phosphor 12 in the cassette 9 set in the cassette stacker 3 based on a control signal from the system control unit 6. It is driven so that the phosphor 12 can be accommodated.

The plate holding section 4 holds the cassette stacker 3
It is possible to take out and hold the stimulable phosphor 12 in a substantially vertical direction from any cassette 9 set in the cassette 9. The plate holding unit 4 is provided with a system control unit 6
, The stimulable phosphor 12 is taken out of the cassette 9 set in the cassette stacker 3, the stimulable phosphor 12 is accommodated in the cassette 9 set in the cassette stacker 3, Drive to move or move.

The image reading section 5 has a sub-scanning section 50 and a main scanning section 51. The main scanning section 51 performs main scanning MS by laser light in the vertical direction, and reads a radiation image recorded on the stimulable phosphor 12 by laser scanning. The main scanning section 51 has a fixed position in the X direction, and the sub-scanning section 50 moves the main scanning section 51 in the Y direction to perform sub-scanning.

As shown in FIG. 13, the system control unit 6 includes a main CPU 60, a device control unit 61, a system disk 62, an image disk 63, and an interface board (hereinafter abbreviated as an I / F board) 65. Have. The main CPU 60 has a CRT of the operation unit 7.
The device control unit 61 of the system control unit 6, the system disk 62, the image disk 63, and the I / F board 65 are connected to each other. The system disk 62 stores a system program for the main CPU 60 to perform overall control such as control of image reading conditions and control of erasing conditions, image processing, image transmission control, and image management, and various data therefor. I have.
The image disk 63 stores an image sent from the device control unit 61 or stores an image subjected to image processing.

The main CPU 60 develops the system program stored in the system disk 62 and various data for the system program in the internal memory,
The image sent from the device control unit 61 or the image subjected to the image processing is stored in the image disk 63 or the image disk 6
3 while controlling the image reading conditions and the erasing conditions while reading out the image stored in
Image transmission and image management are performed.

The operation section 7 corresponds to the input means of the present invention, and has a CRT 70 and a touch panel 71.
Reference numeral 70 denotes a display image transmitted from the main CPU 60, and the touch panel 71 transmits to the main CPU 60 information relating to an instruction input inputted by being touched by the operator.

The main CPU 60 controls overall control of image reading conditions and control of erasing conditions, image processing, image transmission, and image management based on information on instruction input sent from the touch panel 71 of the operation unit 7. Do
In order to display necessary information on the CRT 70, a display image is transmitted to the CRT 70.

When an instruction input including an instruction content for designating any one of the cassettes 9 set in the cassette stacker 3 is input from the operation unit 7, the main CPU 60 is first accommodated in the designated cassette. An instruction screen for instructing input of imaging part information, imaging method information, and imaging sensitivity information of the stimulable phosphor 12 is displayed on the CRT 70.

Then, the apparatus control section 61 determines that the plate holding section 4 has the cassette 9 designated by the instruction input from the operation section 7.
The stimulable phosphor 12 is taken out in a substantially vertical direction and held therefrom, the radiation image recorded on the stimulable phosphor 12 is determined by the laser scanning under the determined image reading condition, and the storage image is read under the determined erasing condition. The plate holding unit 4 holding the stimulable phosphor 12, the image reading unit 5, and the erasing unit 13 are controlled so as to erase the residual image remaining on the luminescent phosphor 12.

The apparatus control section 61 controls the cassette stacker 3, the plate holding section 4, the erasing section 13, the sub-scanning section 50, and the main scanning section 51 to read the radiation image recorded on the stimulable phosphor 12. Read by laser scanning. At this time, the device control unit 61 adjusts the reading gain and the reading scale of the main scanning unit 51 based on the image reading conditions determined and transmitted by the main CPU 60.

Then, the device control section 61 controls the main scanning section 51.
The current / voltage converter (not shown) converts the current signal of the image into a voltage signal. Then, the device control unit 61
Is a logarithmic conversion amplifier (not shown), which performs logarithmic conversion on the image signal converted into a voltage signal, performs A / D conversion with an A / D converter, and sends the obtained digital image to the main CPU 50.

The main CPU 60 is connected via an I / F board 65 to a host computer 66, a diagnostic device 67 and a patient registration terminal 68 outside the main unit 2. Then, the main CPU 60 controls the I / F
The image is transmitted to the host computer 66, the diagnostic device 67, and the patient registration terminal 68 via the board 65.

That is, as shown in FIG. 14, the image reading unit 5 firstly (S1)
The stimulable phosphor 12 is moved in the X direction from the cassette 9 designated by the instruction input from the operation unit 7 to a predetermined X-direction take-out position where the stimulable phosphor 12 can be taken out in a substantially vertical direction. Then, in the second (S2), at the predetermined take-out position in the X direction, the operation unit 7
The stimulable phosphor 12 is taken out from the cassette 9 designated by the instruction input from the scanner 9 in a substantially vertical direction and held. Then, thirdly (S3), the plate holding unit 4 is moved at least in the X direction and stopped at a predetermined reading position in the X direction. Then, in the fourth step (S4), the plate holding unit 4 holding the stimulable phosphor 12 is fixed, and the image reading unit 5 is moved in the Y direction, so that the stimulable phosphor 12 is sub-scanned. Accordingly, the image reading unit 5 reads a radiation image recorded on the stimulable phosphor 12 held by the plate holding unit 4.

[0109] Fifth (S5), when the image reading section 5 finishes reading the radiation image recorded on the stimulable phosphor 12 held in the plate holding section 4, the plate holding section 4 releases the holding image. Up to a predetermined X-direction accommodation position where the stimulable phosphor 12 can be transported and accommodated in the cassette 9 set in the cassette stacker 3 in which the stimulable phosphor 12 has been accommodated. , In the X direction. Then, in the sixth (S6), the stimulable phosphor 12 from which the radiation image has been read by the image reading unit 5 is transported in a substantially vertical direction to the cassette 9 in which the stimulable phosphor 12 is stored. While erasing unit 1
By 3, the afterimage remaining on the stimulable phosphor 12 is erased.

Then, at the upper end of the plate holding portion 4,
An erasing unit 13 is provided. Then, the plate holding unit 4 replaces the stimulable phosphor 12 holding the radiation image read by the image reading unit 5 with the stimulable phosphor 12.
When the plate holder 4 conveys the stimulable phosphor 12 substantially vertically upward based on the erasing conditions determined by the main CPU 60 when the cassette 9 is conveyed substantially vertically upward and accommodated in the cassette 9 in which is stored. While the erasing section 13 irradiates the stimulable phosphor 12 with erasing light, the stimulable phosphor 1 from which the radiation image has been read by the image reading section 5.
2 so as to erase the residual image remaining in the device control unit 61.
Controls the plate holding unit 4 and the erasing unit 13.

The image reading section 5 is built in the apparatus main body 2 of the radiation image reading apparatus, and is arranged below the operation section 7. Sub-scanning unit 50 provided in image reading unit 5
Transports the main scanning unit 51 in the sub-scanning direction.

The sub-scanning section 50 includes a guide shaft 500 and a ball screw 50 in a direction facing the radiation image conversion plate 12.
1 are arranged in parallel. The guide shaft 500 is located above, and the ball screw 501 is located below. The main scanning unit 51 is held vertically by the guide shaft 500 and the ball screw 501 and can be moved horizontally.

The ball screw 501 is provided with a direct drive motor 502.
02 drives the ball screw 501 to rotate the main scan 5
1 is moved in the sub-scanning direction.

As shown in FIG. 11, the main scanning section 51 integrally includes a laser beam generating section 510, a polygon mirror 511, an fθ lens 512, a reflecting mirror 513, a light receiving section 514, and the like. The laser beam generator 510 has a gas laser solid laser, a semiconductor laser, or the like as a light source. The laser beam generator 510 generates a laser beam whose emission intensity is forced as excitation light.

The apparatus controller 61 includes a polygon mirror 51
1 and various origin synchronizing signals and an origin position detection signal from a photo sensor (not shown) for detecting a sub-scanning start position.
1 from the start position while synchronizing with the main scanning by the main scanning unit 5
1 is moved at a predetermined speed in the sub-scanning direction.

Then, the laser beam reaches the polygon mirror 511 via the optical system, is deflected there, is condensed by the fθ lens 512, is deflected by the reflection mirror 513, and is deflected in the optical path by the reflection mirror 513. The light is guided to 12 as scanning light for stimulating excitation. An image is read by receiving photostimulated light emitted by the stimulable phosphor plate 12 scanned by the laser beam by the light receiving unit 514. Light receiving unit 514
The stimulable phosphor emitted from the stimulable phosphor plate 12 is condensed by a flat light condensing plate, is incident on a long photomultiplier, and is photoelectrically converted into an electric signal corresponding to the incident light.
The long photomultiplier of the light receiving unit 514 performs photoelectric conversion into an electric signal corresponding to incident light with a reading gain and a reading scale controlled by the device control unit 61. The output current from the long photomultiplier of the light receiving unit 514 is sent to the device control unit 61.

<Other Embodiments> In the above embodiments, the case where the sub-scanning drive is performed by the ball screw has been described. However, various transmission mechanisms such as gears, gears, toothed belts, and combinations thereof are used. If periodic sub-scanning drive unevenness occurs due to driving of various transmission mechanisms in this case, satisfactory results can be obtained by satisfying the relationship between uP and uB described above.

[0118]

As described in detail above, in the radiation image reading apparatus of the present invention, the spatial frequency u
Polygon unevenness is corrected by selecting and configuring the number of surfaces of the rotary polygon mirror, the reading sampling pitch, and the driving pitch of the sub-scanning driving means so that P and the spatial frequency uB of the sub-scanning driving unevenness do not match each other. The effect of other sub-scanning drive irregularities can be removed from the correction data for this purpose, and accurate correction can be easily performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a configuration example of a stimulable phosphor plate reading unit according to an embodiment of the present invention.

FIG. 3 shows a spatial frequency u of polygon unevenness according to the embodiment.
FIG. 9 is an explanatory diagram showing P and a spatial frequency uB of the sub-scanning drive unevenness.

FIG. 4 is an explanatory diagram showing a pixel arrangement example of image data according to the embodiment of the present invention.

FIG. 5 is a characteristic diagram showing waveforms and frequency characteristics of respective signals according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a state in which an integer multiple of the spatial frequency uP of polygon unevenness and an integer multiple of uB of the spatial frequency of sub-scanning drive unevenness in the embodiment of the present invention are different.

FIG. 7 is an explanatory diagram showing a state in which an integer multiple of the spatial frequency uP of polygon unevenness and an integer multiple of uB of the spatial frequency of sub-scan drive unevenness in the embodiment of the present invention are different.

FIG. 8 is an explanatory diagram showing a state in which an integer multiple of the spatial frequency uP of polygon unevenness and an integer multiple of uB of the spatial frequency of sub-scanning drive unevenness in the embodiment of the present invention are different.

FIG. 9 is an explanatory diagram showing a state in which an integer multiple of the spatial frequency uP of polygon unevenness and an integer multiple of uB of the spatial frequency of sub-scanning drive unevenness in the embodiment of the present invention are different.

FIG. 10 is an explanatory diagram showing a state of a peak remaining rate of polygon unevenness in a power spectrum according to the embodiment of the present invention.

FIG. 11 is a schematic front sectional view of a specific example of the radiation image reading apparatus according to the embodiment of the present invention.

FIG. 12 is a schematic front sectional view of a specific example of the radiation image reading apparatus according to the embodiment of the present invention.

FIG. 13 is a control block diagram of a specific example of the radiation image reading apparatus according to the embodiment of the present invention.

FIG. 14 is a diagram illustrating an operation of a specific example of the radiation image reading apparatus according to the embodiment of the present invention.

FIG. 15 is a schematic diagram of a method of recording an image on a stimulable phosphor plate.

FIG. 16 is a diagram showing a difference between read signals depending on the surface of a polygon mirror and two-dimensional unevenness in a stimulable phosphor plate.

FIG. 17 is an explanatory diagram illustrating a state in which unevenness remains even after correction.

[Explanation of symbols]

 Reference Signs List 101 X-ray source 102 Aperture 103 Subject 104 Stimulable phosphor plate 105 Condenser 106 Photomultiplier 107 Power supply 108 Amplifier 109 Log amp 110 Filter 111 Sampled circuit 112 A / D converter 113 Laser light source 114 Timing circuit 115 Frame memory 116 Controller 117 Printer / automatic machine 132 Polygon scanning mechanism 150 Correction means 151 Correction circuit 152 Correction data creation means 153 Scan correction data memory 154a Polygon correction data memory 154b Inter-polygon correction data memory 155 Sub-scan correction data memory 156 Thinning data Memory 157 Interpolation data creation means 158 Addition means 159 Correction data calculation means 160 Correction data memory

Claims (8)

[Claims] 1. A stimulable phosphor plate on which a radiation image is accumulated and recorded is main-scanned in a first direction by a light beam reflected and deflected by a rotary polygon mirror having a plurality of reflection surfaces, and said light beam The light beam is two-dimensionally projected on the stimulable phosphor plate by sub-scanning the scanning line and the stimulable phosphor plate in the second direction perpendicular to the first direction by the sub-scanning driving means. In a radiation image reading apparatus that obtains an image signal by detecting light generated by the two-dimensional scanning, a polygon unevenness caused by the rotating polygon mirror is corrected for each reflection surface of the rotating polygon mirror. Correction data calculation means for calculating correction data; storage means for storing the correction data; correction means for correcting read image data with the correction data; and unevenness caused by rotation of the rotating polygon mirror. uP the frequency,
Assuming that the spatial frequency of the periodic unevenness caused by the mechanical vibration in the sub-scanning is uB, the number of rotating polygon mirrors, the reading sampling pitch, and the driving of the sub-scanning driving means so that uP and uB do not coincide with each other. A radiation image reading apparatus, wherein a pitch is selected. 2. A stimulable phosphor plate on which a radiation image is accumulated and recorded is main-scanned in a first direction by a light beam reflected and deflected by a rotating polygon mirror having a plurality of reflection surfaces, and the light beam The light beam is two-dimensionally projected on the stimulable phosphor plate by sub-scanning the scanning line and the stimulable phosphor plate in the second direction perpendicular to the first direction by the sub-scanning driving means. In the radiation image reading apparatus that obtains an image signal by detecting light generated by the two-dimensional scanning, the polygon unevenness caused by the rotating polygon mirror is reflected on each reflection surface of the rotating polygon mirror in the main scanning direction. Correction data calculating means for calculating correction data for correcting each position; storage means for storing the correction data; correction means for correcting read image data with the correction data; and a rotating polygon mirror. uP the spatial frequency of the unevenness caused by the rolling,
Assuming that the spatial frequency of the periodic unevenness caused by the mechanical vibration in the sub-scanning is uB, the number of rotating polygon mirrors, the reading sampling pitch, and the driving of the sub-scanning driving means so that uP and uB do not coincide with each other. A radiation image reading apparatus, wherein a pitch is selected. 3. The correction data calculation means calculates correction data based on an average value of image data obtained from a scanning line scanned by the same surface of the rotary polygon mirror. A radiation image reading apparatus according to claim 2. 4. The radiation image reading apparatus according to claim 1, wherein the uP and the uB are different from each other by 2% or more. 5. The radiation image reading apparatus according to claim 1, wherein the uP and the uB are different from each other by 5% or more. 6. The configuration wherein uP and uB are different from each other by (400 / k)% or more, where k is the number of lines per surface averaged for each reflection surface. The radiation image reading device according to claim 3, wherein: 7. The configuration wherein uP and uB are different from each other by (1000 / k)% or more, where k is the number of lines per surface averaged for each reflection surface. The radiation image reading device according to claim 3, wherein: 8. The sub-scanning driving means is driven by a ball screw, and the pitch of the ball screw is D [mm].
8. The radiation image reading apparatus according to claim 1, wherein uB = 1 / D.