JP2001330917A - Radiation image imformation reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove an unevenness occurring in non-aperture part of lens array from the image signals obtained with a radiation image information reader which has the lens arrays like a refractive index distribution type lens array and obtains the image signal by reading the radiation image informations accumulated and recorded at a stimulus phosphor sheet with a line sensor. SOLUTION: An unevenness signal S2 indicating an unevenness occurring in the non-aperture part of the first and second selfoc lens arrays 15 and 16 of an unevenness signal calculating means 32 indicating the positions in the non-apertures of the selfoc lens arrays 15 and 16 is calculated and is stored into a second memory 33. An image signal S1 indicating the radiation images accumulated and recorded at the sheet 50 is stored in a first memory 31. The unevenness is removed from the image signal S1 in accordance with the unevenness signal S2 and the processed image signal S3 is obtained in a correction means 34.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a radiation image information reading apparatus, and more particularly to a radiation image information reading apparatus which reads stimulated emission light emitted from a stimulable phosphor sheet by a line sensor.

[0002]

2. Description of the Related Art When radiation is irradiated, a part of this radiation energy is accumulated, and thereafter, when irradiated with excitation light such as visible light or laser light, a stimulable phosphor that emits stimulated light in accordance with the accumulated radiation energy. (Photostimulable phosphor) is used to temporarily accumulate and record radiation image information of a subject such as a human body on a sheet-shaped stimulable phosphor sheet formed by laminating a stimulable phosphor on a support. An excitation light such as a laser beam is deflected and scanned for each pixel to generate stimulated emission light sequentially from each pixel, and the obtained stimulated emission light is photoelectrically sequentially read by photoelectric reading means to obtain an image signal. A radiation image recording / reproducing system that emits erasing light to the stimulable phosphor sheet after reading the image signal and emits radiation energy remaining on the sheet is widely used in practice.

An image signal obtained by this system is subjected to image processing such as gradation processing and frequency processing suitable for observation and interpretation, and the image signal after these processings is applied as a diagnostic visible image. Filmed or high-definition CR
It is displayed on T and used for diagnosis by a doctor or the like. on the other hand,
The stimulable phosphor sheet from which the residual radiant energy irradiated with the erasing light has been released can store and record radiation image information again, and can be used repeatedly.

Here, in the radiation image information reading apparatus used in the above-mentioned radiation image recording / reproducing system,
From the viewpoint of shortening the reading time of the stimulated emission light, downsizing of the device and cost reduction, a line light source that irradiates the sheet with the excitation light linearly as the excitation light source is used.
As the photoelectric reading means, a line sensor in which a large number of photoelectric conversion elements are disposed along the length direction of the linear portion of the sheet irradiated with the excitation light by the line light source, and the line light source and the line sensor are used. There has been proposed a configuration having a scanning means for moving the sheet relative to the sheet in a direction substantially perpendicular to the length direction of the linear portion (Japanese Patent Application Laid-Open Nos. 60-111568 and 60-236354). No., JP-A-1-10
No. 1540).

Further, in a radiation image information reading apparatus using such a line sensor, in order to increase the degree of condensing the stimulated emission light emitted from each part of the sheet on the line sensor, an object surface and an image surface are required. And a selfoc lens (registered trademark;
A configuration having a gradient index lens array such as an array or a rod lens array is also employed. In this gradient index lens array, a large number of gradient index lenses are arranged corresponding to a large number of photoelectric conversion elements constituting a line sensor, and the photoelectric conversion elements in the line sensor are shown in FIG. When arranged as shown, each of the gradient index lenses of the gradient index lens array is arranged as shown in FIG.

[0006]

However, in the above-described gradient index lens array, there is a non-opening between the gradient index lenses, and an aperture, ie, a lens, exists in the non-opening. The transmittance of stimulated emission light is lower than that of the portion. Here, the stimulated emission light emitted from the stimulable phosphor sheet passes not only through the opening of the gradient index lens array but also through the non-opening, and is condensed on each photoelectric conversion element of the line sensor. For this reason, when the image signal obtained in the radiation image information reading apparatus using the gradient index lens array is reproduced, the reproduced image has the pitch of the non-opening portion of the gradient index lens array and the length of the line sensor. Streaked unevenness extending in a direction perpendicular to the vertical direction appears.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a radiation image information reading apparatus capable of removing streak-like unevenness due to a non-opening portion of a lens array such as a gradient index lens array. It is intended for.

[0008]

According to the present invention, there is provided a radiation image information reading apparatus comprising: a line light source for linearly irradiating a part of a stimulable phosphor sheet on which radiation image information is stored with excitation light; Receiving the stimulated emission light emitted from the portion irradiated in a linear shape of the sheet or the portion on the back side of the sheet corresponding to the irradiated portion, and performing photoelectric conversion. A line sensor provided with a conversion element, and a light collecting means provided between the sheet and the line sensor and including a lens array for collecting the stimulated emission light to each photoelectric conversion element of the line sensor. Scanning means for moving the line light source and the line sensor relative to the sheet in a direction different from the length direction, and sequentially reading the output of the line sensor in accordance with the movement. A radiation image information reading apparatus comprising: a reading unit that obtains an image signal representing the radiation image information; and a processing that removes unevenness caused by a non-opening of the lens array on the image signal. And a removal processing means for obtaining a completed image signal.

As a line light source, a fluorescent lamp, a cold cathode fluorescent lamp, an LED array or the like can be applied. In addition, the line light source is not limited to a light source itself having a linear shape as in the above-described fluorescent lamp or the like, and may be a light source in which emitted excitation light is linear, and includes a broad area laser and the like. . The excitation light emitted from the line light source may be one that is continuously emitted, or may be pulsed light that is emitted in a pulse shape that repeats emission and stop, but from the viewpoint of noise reduction, It is desirable to use high-power pulsed light.

It is desirable that the length of the irradiation area on the stimulable phosphor sheet by the excitation light emitted from the line light source in the major axis direction is longer than or equal to one side of the stimulable phosphor sheet. In this case, the excitation light may be emitted while being inclined with respect to the side of the sheet.

Here, in order to improve the degree of condensing the excitation light emitted from the light source on the sheet, a cylindrical lens, a slit, a gradient index lens array, a fluorescent light guide sheet, an optical fiber bundle, or the like, Is preferably disposed between the light source and the sheet. When the optimal secondary excitation wavelength of the stimulable phosphor sheet is around 600 nm, the activator of the phosphor is Eu3 +.
(Emission center) and preferably a glass or polymer medium.

It is appropriate that the light beam width of the excitation light emitted from the light source on the sheet is 10 to 4000 μm.

As the line sensor, an amorphous silicon sensor, a CCD sensor, a CCD with a back illuminator, a MOS image sensor, or the like can be applied.

The lens array of the light condensing means is preferably a gradient index lens array.

The lens array of the light condensing means has a one-to-one correspondence between the object plane and the image plane in order to increase the degree of condensing the stimulated emission light emitted from each part of the sheet on the line sensor. It consists of a selfoc lens array, a rod lens array, etc., configured with an imaging system that
It is composed of glass and polymer materials.

In addition, it is desirable to use a cylindrical lens, a slit, an optical fiber bundle, or a combination thereof in order to further increase the degree of light collection, in addition to the lens array, as the light collecting means.

Further, between the sheet and the line sensor,
It is preferable to provide an excitation light cut filter (a sharp cut filter, a band pass filter) that transmits the stimulating light but does not transmit the excitation light to prevent the excitation light from entering the line sensor.

The size of the light receiving surface of each of a large number of photoelectric conversion elements constituting the line sensor is determined by the amount of stimulated emission light emitted from the sheet irradiated with the above-described light beam width by the excitation light.
It is set smaller than the light beam width on the light receiving surface of the line sensor, and a plurality of photoelectric conversion elements are provided in the length direction (long axis direction) of the light beam. It is set longer than this.

The line sensor may be configured by arranging a plurality of photoelectric conversion elements in the width direction (shorter axis direction) of the light beam. In this case, it is preferable that 4 or more and 12 or less photoelectric conversion elements are provided in a direction orthogonal to the length direction. Further, the plurality of photoelectric conversion elements are not limited to those arranged in a matrix arranged in a straight line in any of the major axis direction and the minor axis direction.
A zigzag arrangement in which the lines are arranged in a straight line but in the short axis direction in a zigzag pattern, a zigzag arrangement in which the lines are arranged in a straight line in the short axis direction but in a zigzag form in the long axis direction, and a zigzag arrangement in both axis directions They may be arranged in a staggered arrangement. Further, it is preferable that the opening of the lens array is provided corresponding to each photoelectric conversion element of the line sensor.

In a configuration in which the number of photoelectric conversion elements is increased so as to be affected by the transfer rate, a memory element corresponding to each photoelectric conversion element is provided, and the charge accumulated in each photoelectric conversion element is temporarily stored. A configuration may be employed in which the charge is stored in each memory element and the charge is read out from each memory element during the next charge storage period, thereby avoiding a reduction in the charge storage time due to an increase in the charge transfer time.

It is desirable that the number of photoelectric conversion elements provided in the long axis direction of the line sensor is 1000 or more.
It is desirable that the length of the line sensor be longer than one side of the sheet or equivalent on the light receiving surface.

The direction in which the line light source and the line sensor are moved relative to the sheet by the scanning means (the direction different from the length direction) is a direction substantially orthogonal to the length direction. That is, it is desirable that the direction is the short axis direction. However, the direction is not limited to this direction. For example, as described above, in a configuration in which the line light source and the line sensor are longer than one side of the sheet, the line extends over substantially the entire surface of the sheet. Within a range in which the excitation light can be evenly irradiated, the light source and the line sensor may be moved in an oblique direction deviating from a direction substantially perpendicular to the length direction, or may be moved in a zigzag shape, for example. The movement may be performed by changing the direction.

The line light source and the line sensor may be arranged on the same side of the sheet, or may be arranged separately on the opposite sides. However, if you ’re using a separate configuration,
It is necessary to make the support of the sheet transparent to the stimulating light so that the stimulating light is transmitted to the surface of the sheet opposite to the surface on which the excitation light is incident.

The removal processing means includes: an unevenness signal calculating means for calculating an unevenness signal representing the unevenness based on the position of the non-opening of the lens array; a storage means for storing the unevenness signal; It is preferable that the image processing apparatus further includes a correction unit that corrects the image signal based on the signal.

Here, the unevenness signal is calculated as a one-dimensional signal having data only in the direction in which the lens array extends.

Further, the removal processing means includes a storage means for storing a reference image signal obtained from a stimulable phosphor sheet on which radiation image information of a uniform density as a reference is stored and recorded, and a storage means for storing the reference image signal. And correcting means for correcting the image signal.

Here, the reference image signal is a two-dimensional signal corresponding to the entire surface of the stimulable phosphor sheet.

[0028]

According to the present invention, since the unevenness caused by the non-opening of the lens array such as the gradient index lens array is removed from the image signal, the image signal is reproduced, and thus the lens array is reproduced. Thus, a clear image without streak-like unevenness due to the non-opening portion can be obtained.

[0029] In addition, the line sensor is provided with a plurality of photoelectric conversion elements also in a direction orthogonal to the length direction of the line sensor, thereby improving the light-collecting efficiency of stimulated emission light by the line sensor. Can be.

Since the unevenness is caused by the non-opening of the lens array, the unevenness signal can be represented as a one-dimensional signal extending in the long axis direction of the line sensor. Therefore, if the unevenness signal is calculated based on the position of the non-opening portion of the lens array, the capacity of the storage unit for storing the unevenness signal may be relatively small.
The configuration of the device can be simplified.

Further, when a reference image signal is obtained from a stimulable phosphor sheet on which radiation image information of a uniform density as a reference is accumulated and recorded, since this reference image signal is a two-dimensional signal, the capacity of the storage means is increased. Is relatively large, but the reference image signal includes uneven irradiation of the sheet (two-dimensional unevenness), unevenness of the sensitivity of the sheet (two-dimensional unevenness), unevenness of the excitation light irradiation (one-dimensional unevenness), and stimulated emission light. (Uniform unevenness) until the is input to the line sensor, sensitivity unevenness (one-dimensional unevenness) of the line sensor, and the like. Therefore, if the image signal is corrected using the reference image signal, the processed image signal obtained will have those unevenness removed.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing a configuration of a radiation image information reading apparatus according to an embodiment of the present invention, wherein FIG.
(B) shows the I- of the radiation image information reading apparatus shown in (a).
FIG. 2 is a sectional view taken along the line I, and FIG. 2 is a view showing a detailed configuration of the line sensor 20 of the reading apparatus shown in FIG.

The illustrated radiation image information reading apparatus has a stimulable phosphor sheet (hereinafter, referred to as a stimulable phosphor sheet) on which radiation image information is stored.
A scanning belt 40 on which a sheet 50 is placed and conveyed in the direction of arrow Y, a linear secondary excitation light (hereinafter referred to as
A broad area laser (hereinafter, referred to as BLD) 11, BL which emits an excitation light (hereinafter simply referred to as L) substantially parallel to the surface of the sheet 50.
An optical system 12 comprising a combination of a collimator lens for condensing the linear excitation light L emitted from D11 and a toric lens for expanding the beam only in one direction, which is arranged at an angle of 45 degrees with respect to the surface of the sheet 50. Further, a dichroic mirror 14, which is set so as to reflect the excitation light L and transmit a stimulated emission light M to be described later, and a linear excitation light L reflected by the dichroic mirror 14, is placed on the sheet 50 in the direction of arrow X. The linearly stimulating luminescence light M according to the stored and recorded radiation image information, which is condensed into a linear shape (line width of about 100 μm) extending along the line and the linear excitation light L is condensed and emitted from the sheet 50. A gradient index lens array (a lens in which a number of gradient index lenses are disposed, hereinafter referred to as a first selfoc lens array) 15 for forming a parallel light beam; A second selfoc lens array 16 for condensing the stimulated emission light M, which has been converted into a parallel light beam by the lens array 15 and has passed through the dichroic mirror 14, on a light receiving surface of each photoelectric conversion element 21 constituting a line sensor 20 described later; An excitation light cut filter 17 that cuts the excitation light L reflected on the surface of the sheet 50 and transmits the excitation light M, which is slightly mixed with the stimulated emission light M transmitted through the second selfoc lens array 16; A line sensor 20 in which a large number of photoelectric conversion elements 21 that receive the photostimulated emission light M transmitted through the cut filter 17 and perform photoelectric conversion are provided, and a signal output from each photoelectric conversion element 21 configuring the line sensor 20 is output. , By sequentially reading according to the movement of the sheet 50,
It has a reading unit 29 for obtaining an image signal S1 representing radiation image information stored and recorded in a storage unit, and a processing unit 30 for performing processing for removing unevenness on the image signal S1 as described later.

The optical system 12 composed of a collimator lens and a toric lens expands the excitation light L from the BLD 11 onto a dichroic quick mirror 14 to a desired irradiation area.

In detail, as shown in FIG. 2, the line sensor 20 includes a large number (for example, 1000 or more) of photoelectric conversion elements 21 arranged along the long axis direction (the direction of arrow X in FIG. 1). The rows of the photoelectric conversion elements 21 extending in the direction of the arrow X are arranged in a zigzag manner so as to be arranged in a zigzag manner in three rows in the conveying direction of the sheet 50 (the direction of the arrow Y). Also, the line sensor 20
Each of these photoelectric conversion elements 21 constituting a vertical
The light receiving surface has a size of about 100 μm × 100 μm in width, and the size is 100 μm in length on the surface of the sheet 50.
X This is a size that receives the stimulated emission light M emitted from a portion having a size of about 100 μm in width. Note that the photoelectric conversion element 21 is specifically an amorphous silicon sensor, a CCD, or the like.
A sensor, a MOS image sensor, or the like can be applied.

FIG. 3 is a diagram showing the structure of the first and second Selfoc lens arrays 15 and 16. As shown in FIG. 3, the first and second Selfoc lens arrays 15, 16
In the figure, a plurality of gradient index lenses 18 are provided so as to correspond to the respective photoelectric conversion elements 21 of the line sensor 20. Further, the first selfoc lens array 15 has an effect that the light emission area of the photostimulated light M on the sheet 50 is formed on the dichroic mirror 14 as an image plane which forms an image with a one-to-one size. 2 is a dichroic mirror on the light receiving surface of the photoelectric conversion element 21.
The image of the stimulated emission light M on the image 14 is formed into an image plane on which the image is formed in a one-to-one size.

The processing means 30 comprises a first memory 31, first and second memories 31 for storing image signals S1 obtained by the reading means 29 and representing the radiation image information accumulated and recorded on the sheet 50.
A non-uniform signal calculating means 32 for calculating a non-uniform signal S2 representing non-uniformity caused by the non-opening portions 19 of the selfoc lens arrays 15 and 16, a second memory 33 for storing the non-uniform signal S2, and a non-uniform signal for the image signal S1. A correction means 34 is provided for obtaining a processed image signal S3 by removing unevenness due to the non-opening portions 19 of the first and second selfoc lens arrays 15 and 16 from the image signal S1 by correcting the image signal S1.

Here, in the first and second SELFOC lens arrays 15 and 16, a non-opening 19 exists between the gradient index lenses 18 as shown in FIG.
In the case of, the transmittance of the stimulating light M is reduced as compared with the portion where the lens 18 exists. Here, the stimulated emission light M emitted from the sheet 50 is not only the lens 18 of the first and second SELFOC lens arrays 15 and 16 but also the non-opening portion 19.
And is condensed on each photoelectric conversion element 21 of the line sensor 20. For this reason, the image signal S1 obtained by the line sensor 20 includes a non-opening portion in the longitudinal direction of the line sensor 20.
A line-shaped unevenness having a pitch of 19 and extending in the short axis direction of the line sensor 20 appears. That is, when an image signal is obtained by storing and recording a CTF chart as shown in FIG. 4 on the stimulable phosphor sheet 50, if there is no noise or unevenness, the profile in the direction of the arrow X is as shown in FIG. . However, when the first and second SELFOC lens arrays 15 and 16 are used, streak-like unevenness due to the non-opening portion 19 is included in the image signal as shown in FIG. Will be deteriorated.

For this reason, in the present embodiment, the unevenness signal calculating means 32 calculates and corrects the unevenness signal S2 representing the unevenness caused by the non-opening portion 19 of the first and second Selfoc lens arrays 15 and 16. The means 34 removes unevenness from the image signal S1 based on the unevenness signal S2 to obtain a processed image signal S3.

Here, the pitch of the non-opening portions 19 of the first and second selfoc lens arrays 15 and 16 is known.
From this pitch, the position where unevenness appears in the radiation image information reading apparatus according to the present embodiment can be obtained.
Also, the difference between the transmittance of the gradient index lens 18 and the transmittance of the non-opening 19 is known. Therefore, the unevenness signal calculating means 32 is configured to use the first and second selfoc lens arrays 1
A one-dimensional unevenness signal S2 having a profile as shown in FIG. 7 is calculated from the pitch of the non-opening portions 19 in 5 and 16 and the difference between the transmittance of the lens 18 and the transmittance of the non-opening portions 19. In FIG. 7, the pixel position where the peak in the uneven signal S2 appears does not correspond to the pixel position in FIG.

The intensity of unevenness due to the non-opening portion 19 may vary depending on imaging conditions and reading conditions such as the intensity of radiation and the intensity of excitation light L when storing and recording radiation image information on the stimulable phosphor sheet 50. different. For this reason, the correction means 34 adjusts the value of the unevenness signal S2 according to the photographing condition and the reading condition to correct the image signal S1 as shown in the following equation (1), thereby obtaining the processed image signal. S3 is obtained. This correction is performed for each scanning line of the image signal S1.

S 3 = S 1 / (k · S 2) (1) k: Coefficient for Changing the Intensity of the Uneven Signal S 2 Next, the operation of the radiation image information reading apparatus of the present embodiment will be described.

First, by moving the scanning belt 40 in the direction of the arrow Y, the sheet 50 on which the radiation image information is stored is transported in the direction of the arrow Y.

On the other hand, the BLD 11 emits the linear excitation light L substantially parallel to the surface of the sheet 50, and the excitation light L is transmitted to the optical system 12 comprising a collimator lens and a toric lens provided on the optical path. Is a parallel beam, is reflected by the dichroic mirror 14, travels in a direction perpendicular to the surface of the sheet 50, and is extended by the first selfoc lens array 15 on the sheet 50 along the arrow X direction. It is condensed in a shape.

The linear excitation light L incident on the sheet 50 excites the stimulable phosphor in the light condensing area, enters the sheet 50 from the light condensing area, and diffuses into the vicinity of the light condensing area. The stimulable phosphor near the focusing area is also excited. As a result,
From the light condensing area of the sheet 50 and the vicinity thereof, photostimulated light M having an intensity corresponding to the stored and recorded radiation image information is emitted.

The stimulated emission light M emitted from the sheet 50 is converted into a parallel light beam by the first selfoc lens array 15, transmitted through the dichroic mirror 14, and transmitted to the line sensor 20 by the second selfoc lens array 16. The light is condensed on the light receiving surface of each of the constituent photoelectric conversion elements 21. At this time, the second
Stimulated light M transmitted through the SELFOC lens array 16
Excitation light L reflected on the surface of the sheet 50 slightly mixed with
Is cut by the excitation light cut filter 17.

The line sensor 20 photoelectrically converts the stimulated emission light M received by each photoelectric conversion element 21, and each signal Q obtained by the photoelectric conversion is input to the reading means 29. Reading means
Reference numeral 29 denotes an A / D conversion of the input signal Q, and stores the signal Q in correspondence with a portion of the sheet 50. When the signal Q is obtained over the entire surface of the sheet 50, an image representing a radiation image accumulated and recorded on the sheet 50 is stored. The signal S1 is output. The image signal S1 is input to the processing means 30 and stored in the first memory 31.

On the other hand, the unevenness signal calculating means 32 calculates the unevenness signal S2 in advance, and the calculated unevenness signal S2 is stored in the second memory 33. The correction means 34 is a first memory
The image signal S1 from the second memory 33 and the uneven signal S from the second memory 33
2 is read out, and the operation shown in the above equation (1) is performed between the corresponding pixels to remove unevenness caused by the non-opening portions 19 of the first and second selfoc lens arrays 15 and 16 from the image signal S1. The processed image signal S3 is obtained by the removal. The processed image signal S3 is input to an image processing means (not shown), where the image signal is subjected to various image processing and provided for reproduction.

As described above, according to the present embodiment, the non-opening portions of the first and second Selfoc lens arrays 15 and 16 are provided.
Since the unevenness due to 19 is removed from the image signal S1, it is possible to obtain a processed image signal S3 that can reproduce a clear image without streaky unevenness having a pitch of the non-opening portion 19.

In the above embodiment, the unevenness signal calculating means 32 calculates the unevenness signal S2. However, the stimulable phosphor sheet 50 which has been uniformly exposed to the radiation is used as the radiation image information reading apparatus according to the present embodiment. The first and second selfoc lens arrays 15,
An unevenness signal S2 'for correcting unevenness caused by the 16 non-opening portions 19 may be obtained. FIG. 8 shows the unevenness signal S
FIG. 3 is a schematic block diagram showing a configuration of a processing unit 30 'for correcting the image signal S1 by 2'. As shown in FIG. 8, the processing means 30 'includes a third memory 35 for storing the unevenness signal S2' instead of the unevenness signal calculating means 32 and the second memory 33 in the processing means 30.

Hereinafter, acquisition of the unevenness signal S2 'when the processing means 30' shown in FIG. 8 is used will be described.

First, a signal Q 'obtained from the line sensor 20 by reading the stimulable phosphor sheet 50 uniformly exposed to radiation is input to the reading means 29. The reading means 29 performs A / D conversion of the signal Q ', and
When a signal Q 'is obtained on the entire surface of the sheet 50, an uneven signal S2' is output. The uneven signal S2 'is stored in the third memory 35. in this case,
The uneven signal S2 'becomes a two-dimensional image signal and the uneven signal S
Since it is necessary to perform alignment between 2 ′ and the image signal S1, it is possible to use a marker when accumulating and recording a radiographic image on the sheet 50, or to form a notch for alignment on the sheet 50. desirable.

When the image signal S1 is stored in the first memory 31, the correction means 34 reads the image signal S1 from the first memory 31 and the uneven signal S2 'from the third memory 35, respectively. The operation shown in the above equation (1) is performed between the corresponding pixels to remove the unevenness caused by the non-opening portions 19 of the first and second SELFOC lens arrays 15 and 16 from the image signal S1 and process the processed image. The signal S3 is obtained. The processed image signal S3 is input to an image processing means (not shown), where the image signal is subjected to various image processing and provided for reproduction.

In this manner, the unevenness caused by the non-opening portions 19 of the first and second selfoc lens arrays 15 and 16 can be removed from the image signal S1, so that the stripe having the pitch of the non-opening portions 19 can be removed. It is possible to obtain a processed image signal S3 capable of reproducing a clear image without unevenness in shape.

The unevenness signal S2 'includes unevenness of irradiation of the sheet 50 (two-dimensional unevenness), unevenness of sensitivity of the sheet 50 (two-dimensional unevenness), unevenness of irradiation of the excitation light L (one-dimensional unevenness),
Since unevenness in efficiency (one-dimensional unevenness) until the stimulated emission light M is input to the line sensor 20 and unevenness in sensitivity (one-dimensional unevenness) of the line sensor 20 are included, the image signal S1 is corrected by the unevenness signal S2 '. In this case, the obtained processed image signal S3 is a signal from which such unevenness has been removed.

The radiation image information reading apparatus of the present invention is not limited to the above-described embodiment, but includes a light source, a condensing optical system between the light source and the sheet, an optical system between the sheet and the line sensor, and a line. Various known structures can be employed as the sensor or the adding means. In addition, the image processing apparatus further includes an image processing device that performs various signal processing on signals output from the image information reading unit, and an erasing unit that appropriately emits radiation energy still remaining on the sheet whose excitation has been completed. An equipped configuration can also be adopted.

The line sensor 20 according to the present embodiment
Represents that the photoelectric conversion element 21 is a line sensor as shown in FIG.
Although they are arranged in a zigzag pattern, they are arranged in a straight line in the length direction (long axis direction) of 20, but in a zigzag manner in the short axis direction (arrow Y direction) orthogonal to the long axis direction. The line sensor 20 used in the radiation image information reading apparatus according to the present invention is not limited to the one in such an embodiment, and FIG.
As shown in FIG. 9 (b), the photoelectric conversion elements 21 are arranged in a matrix in which the photoelectric conversion elements 21 are arranged in a straight line in both the major axis direction and the minor axis direction. In the direction, they may be arranged in a straight line, but in the long axis direction they may be arranged in a zigzag manner. Further, FIG.
As shown in (c), the photoelectric conversion elements 21 may be arranged so as to be aligned in one straight line only in the long axis direction. FIG.
As shown in (d), the photoelectric conversion elements 21 may be arranged in a staggered manner such that the rows of the photoelectric conversion elements 21 are arranged in a zigzag manner in four rows in the short axis direction. Note that the arrangement of the photoelectric conversion elements 21 in the minor axis direction is preferably 12 or less. The SELFOC lens arrays 15 and 16 may be provided with the gradient index lenses 18 corresponding to the positions of the photoelectric conversion elements 21.

Further, in the radiation image information reading apparatus according to the above-described embodiment, the optical path of the excitation light L and the stimulated emission light M
Although the configuration in which the optical path partially overlaps with that of the above is adopted to further reduce the size of the device, the present invention is not limited to such a configuration. For example, as shown in FIG. A configuration in which the optical path of L and the optical path of stimulated emission light M do not overlap at all can be applied.

That is, the illustrated radiation image information reading apparatus includes a scanning belt 40, a BLD 11 that emits linear excitation light L at an angle of approximately 45 degrees with respect to the surface of the sheet 50, and a linear excitation light L emitted from the BLD 11. An optical system 12 that irradiates a linear excitation light L onto the surface of the sheet 50, and is inclined by approximately 45 degrees with respect to the surface of the sheet 50. Each of the photoelectric conversion elements constituting a line sensor 20 which has a light axis substantially perpendicular to the direction of travel of the excitation light L and emits stimulated emission light M emitted from the sheet 50 by irradiation of the excitation light L
Selfoc lens array 16, which focuses light on the light receiving surface of 21,
Excitation light cut filter 1 that cuts off excitation light L mixed with photostimulated light M incident on selfoc lens array 16
7. A line sensor 20 provided with a large number of photoelectric conversion elements 21 for receiving and stimulating the photostimulated emission light M transmitted through the excitation light cut filter 17, and output from each photoelectric conversion element 21 constituting the line sensor 20. The read signal Q is read and the image signal S
1 and a processing unit 30 for performing a process of removing unevenness as described above for the image signal S1.

In the radiation image information reading apparatus of each of the above embodiments, both the light source of the excitation light and the line sensor are arranged on the same surface side of the sheet, and the stimulus emitted from the sheet surface on which the excitation light enters is provided. Although the configuration of the reflected light condensing type in which the emitted light is received is adopted, the radiation image information reading apparatus of the present invention is not limited to such a configuration, and the support has a photostimulable emission light transmitting property. By using the stimulable phosphor sheet formed of the above material, as shown in FIG.
A transmitted light condensing type in which a light source of excitation light and a line sensor are arranged on different sides of a sheet to receive stimulated emission light emitted from a surface opposite to the sheet surface on which the excitation light is incident. May be adopted.

That is, in the illustrated radiation image information reading apparatus, the stimulable phosphor sheet 50 has a front end portion and a rear end portion (no radiation image is recorded at the front end portion and the rear end portion, or the radiation image is recorded at the front end and the rear end portion). Is also not a region of interest), a transport belt 40 'for transporting the sheet in the direction of arrow Y while supporting it, and BLD11 emitting linear excitation light L in a direction substantially perpendicular to the surface of the sheet 50, and exiting from the BLD11. An optical system 1 for irradiating the linear excitation light L to the surface of the sheet 50, comprising a combination of a collimator lens for condensing the linear excitation light L and a toric lens for expanding the beam only in one direction.
2. An excitation light L having an optical axis substantially orthogonal to the surface of the sheet 50,
The stimulated emission light M 'emitted from the back surface of the sheet 50 (the surface opposite to the incident surface of the excitation light L) by the irradiation of the light is irradiated onto the light receiving surface of each photoelectric conversion element 21 constituting the line sensor 20 described later. The selfoc lens array 16 to be condensed, the excitation light cut filter 17 for cutting the excitation light L mixed with the stimulated emission light M ′ incident on the selfoc lens array 16, and the stimulated emission light transmitted through the excitation light cut filter 17 A line sensor 20 provided with a large number of photoelectric conversion elements 21 for receiving and receiving M ′ and performing photoelectric conversion, and each photoelectric conversion element 21 constituting the line sensor 20
And a processing unit 30 for reading the signal Q output from the CPU to obtain the image signal S1 and processing the image signal S1 to remove unevenness as described above.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a radiation image information reading apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a detailed configuration of a line sensor.

FIG. 3 is a diagram showing a detailed configuration of a selfoc lens array.

FIG. 4 is a diagram showing a CTF chart;

FIG. 5 is a diagram showing a profile of an image signal obtained from a CTF chart (without unevenness).

FIG. 6 is a diagram showing a profile of an image signal obtained from a CTF chart (including unevenness);

FIG. 7 is a diagram showing a profile of an unevenness signal;

FIG. 8 is a schematic block diagram showing the configuration of another embodiment of the processing means.

FIG. 9 is a diagram showing another arrangement state of the photoelectric conversion elements constituting the line sensor.

FIG. 10 is a configuration diagram showing another embodiment of the radiation image information reading apparatus of the present invention (part 1).

FIG. 11 is a configuration diagram showing another embodiment of the radiation image information reading apparatus of the present invention (part 2).

[Explanation of symbols]

11 Broad area laser (BLD) 12 Optical system composed of collimator lens and toric lens 14 Dichroic mirror 15, 16 Selfoc lens array 17 Excitation light cut filter 20 Line sensor 21 Photoelectric conversion element 29 Reading means 30 Processing means 31 First memory 32 Uneven signal calculation means 33 Second memory 34 Correction means 35 Third memory 40 Scanning belt 50 Storable phosphor sheet L Excitation light M Stimulated emission light

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Claims (8)

[Claims] 1. A line light source for irradiating a part of a stimulable phosphor sheet on which radiation image information is accumulated and recorded with excitation light in a linear manner, a linearly irradiated part of the sheet or this irradiated part. A line sensor in which a plurality of photoelectric conversion elements are disposed in the length direction of the portion, which receives the photostimulated light emitted from the portion on the back surface side of the sheet corresponding to and performs photoelectric conversion. A light-condensing means disposed between the line sensor and a lens array for condensing the stimulated emission light on each photoelectric conversion element of the line sensor; and the line light source and the line sensor for the sheet. Scanning means for relatively moving in a direction different from the length direction, and reading means for sequentially reading the output of the line sensor in accordance with the movement to obtain an image signal representing the radiation image information. The radiation image information reading apparatus according to claim 1, further comprising a removal processing unit configured to perform a process of removing unevenness caused by the non-opening portion of the lens array on the image signal to obtain a processed image signal. Radiation image information reading device. 2. The radiation image information reading apparatus according to claim 1, wherein the line sensor has a plurality of photoelectric conversion elements arranged also in a direction orthogonal to the length direction. 3. The radiation image information reading apparatus according to claim 2, wherein the line sensor is provided with 4 to 12 photoelectric conversion elements in a direction orthogonal to the length direction. 4. The radiation image information reading apparatus according to claim 2, wherein the photoelectric conversion elements of the line sensor are arranged in a staggered manner. 5. The radiation image information according to claim 1, wherein an opening of the lens array is provided corresponding to each photoelectric conversion element of the line sensor. Reader. 6. The radiation image information reading apparatus according to claim 1, wherein the lens array is a gradient index lens array. 7. An unevenness signal calculating means for calculating an unevenness signal indicating the unevenness based on a position of a non-opening portion of the lens array, a storage means for storing the unevenness signal, 7. The radiation image information reading apparatus according to claim 1, further comprising: a correction unit configured to correct the image signal based on the uneven signal. 8. A storage unit for storing a reference image signal obtained from a stimulable phosphor sheet on which radiation image information having a uniform density as a reference is stored and stored, wherein the storage unit stores a reference image signal based on the reference image signal. The radiation image information reading apparatus according to claim 1, further comprising: a correction unit configured to correct the image signal.