JP2002185703A - Radiation image information reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accelerate the processing speed of A/D conversion and to eliminate high frequency noise in a radiation image information reader using a line sensor composed by arraying CCDs. SOLUTION: In a signal processing means 29, output from the respective CCDs 21 of the line sensor 20 is read by a read means 30, analog image signals Q obtained by the read are outputted to a sampling processing means 31, a double correlation sampling processing is executed and image signals S1 are obtained. The image signals S1 are logarithmically transformed by a logarithmic transformation means 32 and logarithmically transformed image signals S2 are obtained. The high frequency noise is eliminated from the image signals S2 by an anti-aliasing filter 33 and noise-eliminated image signals S3 are obtained. The image signals S3 are inputted to an A/D conversion means 34 and A/D-converted and digital image signals S4 are obtained.

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 for reading out stimulated emission light emitted from a stimulable phosphor sheet by a line sensor in which CCDs are arranged.

[0002]

2. Description of the Related Art When radiation is irradiated, a part of the radiation energy is accumulated. Then, when irradiation with excitation light such as visible light or laser light is performed, an accumulated light exhibiting stimulated emission according to the accumulated radiation energy is emitted. Phosphor (stimulable phosphor)
The excitation light, such as laser light, is used to temporarily accumulate and record radiation image information of a subject such as a human body on a sheet-like stimulable phosphor sheet in which a stimulable phosphor is laminated on a support. Deflection scanning generates stimulated emission light, and the stimulated emission light is photoelectrically read by photoelectric reading means to obtain an image signal. On the other hand, after the image signal is read, erasing light is applied to the stimulable phosphor sheet. Radiation image recording / reproducing systems that irradiate and emit radiation energy remaining on the sheet to enable reuse of the stimulable phosphor sheet have been widely put to practical use.

Image signals obtained by these systems are subjected to image processing such as gradation processing and frequency processing suitable for observation and interpretation, and image signals after these processings are applied to a diagnostic visible image. (Final image) recorded on film,
Alternatively, it is displayed on a high-definition CRT and used for diagnosis by a doctor or the like.

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, and reducing the size and cost of the apparatus, a line light source that irradiates the sheet with excitation light linearly is used as the excitation light source.
As the photoelectric reading means, a line sensor in which a large number of CCDs are arranged along a length direction (hereinafter, referred to as a main scanning direction) of a linear portion of a sheet irradiated with excitation light by a line light source is used. And moving one of the line light source and the line sensor and the phosphor sheet relative to the other in a direction substantially perpendicular to a length direction of the linear portion (hereinafter referred to as a sub-scanning direction). Configurations having scanning means have been proposed (JP-A-60-111568, JP-A-6-111568).
0-236354, JP-A-1-101540).

[0005] In addition, because of the remarkable improvement in performance such as increase in the number of pixels, improvement in sensitivity, reduction in noise, and reduction in image size due to the innovation of semiconductor fine processing technology, the CCD constituting the above-mentioned line sensor includes: CCD is often used.

In the case of a CCD, as shown in FIG. 7, as a photoelectric conversion output characteristic, there is a feed-through period between a reset period and a signal output period. Is a value obtained by subtracting the value of the signal level during the feedthrough period (hereinafter referred to as the reference level) from the value of the signal level during the signal output period (hereinafter referred to as the signal level).

On the other hand, in the above-described radiation image information reading apparatus, the image signal obtained by the line sensor is an analog signal and needs to be converted into a digital signal. Conventionally, according to the above-described output characteristics of a CCD, an analog image signal from a line sensor using a CCD is digitized in a linear area before logarithmic conversion, and then converted to a digital signal in a digital area.
A technique of performing multiple correlation sampling and subtracting a reference level value from a signal level value to obtain a digital signal representing a radiation image is often used.

[0008]

By the way, in the conventional digitizing method, A / A is calculated in a linear area before logarithmic conversion.
Since D conversion is performed, the minimum resolution is small, and the number of bits must be increased to achieve a sufficient resolution.
Therefore, there is a problem that the data amount increases and processing time is required.

[0009] The signal output from the line sensor contains various noises, and the frequency components higher than the Nyquist frequency are almost noise components. In order to remove the high frequency noise, it is necessary to apply an anti-aliasing filter before digitizing the image signal. However, as in the related art, a digitizing method for performing double correlation sampling after digitizing the image signal When using an anti-aliasing filter before digitizing from the output characteristics of the CCD,
Since the signal level and the reference level are disturbed, an accurate image signal cannot be obtained. Therefore, the image signal is digitized without applying the anti-aliasing filter, and a digital signal including high-frequency noise can be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides an image signal processing apparatus in a radiation image information reading apparatus that can reduce the time for digitization processing and can also remove high frequency noise. It is intended for.

[0011]

According to the present invention, there is provided a radiation image information reading apparatus comprising: a line light source for irradiating a part of a stimulable phosphor sheet storing radiation image information with excitation light in a linear manner;
A plurality of CCDs in the length direction of the portion, which receive the stimulated emission light emitted from the portion irradiated on a part of the sheet or the back surface of the sheet corresponding to the irradiated portion and perform photoelectric conversion; A scanning unit for moving the line light source and the line sensor relative to the sheet in a direction different from the length direction, and a line sensor from each CCD of the line sensor. By sequentially reading the output according to the movement, in addition to a reading unit that obtains an analog image signal representing the radiation image information,
Sampling means for performing double correlation sampling processing on the analog image signal, logarithmic conversion means for performing logarithmic conversion on the double-sampled image signal, and A / D conversion for the logarithmically converted image signal And A / D conversion means for obtaining a digital image signal.

Further, the image signal processing apparatus of the present invention includes an anti-aliasing filter, and performs an anti-aliasing filter process on the image signal subjected to the double sampling process before performing A / D conversion. It can be carried out.

Here, the line light source may be any one that irradiates the stimulable phosphor sheet with excitation light linearly.
An LED, an organic EL, a fluorescent lamp, a high-pressure sodium lamp, a cold cathode tube or the like can be applied. In addition, an expansion mechanism that expands the excitation light so that the excitation light emitted as the light source itself is not only linear but also linear on the irradiation surface of the stimulable phosphor sheet may be used.

[0014] The excitation light emitted from the line light source may be emitted continuously or may be pulsed light emitted in a pulse shape in which emission and stop are repeated. From the viewpoint, it is desirable that the light is pulsed light with high output. The emission wavelength of the line light source may be any wavelength that can generate stimulated emission light by irradiating the stimulable phosphor sheet with excitation light. In combination use, 600-1000 nm, more preferably 6 nm
It shall be 00-700 nm.

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 irradiation may be performed such that the excitation light is irradiated on the sheet while being inclined.
Further, in order to further improve the light-collecting efficiency of the excitation light emitted from the line light source on the sheet, a refractive index distribution of a cylindrical lens, a slit, a selfoc lens (registered trademark), an array of rod lenses, etc. Shaped lens arrays, fiber optic bundles, etc., or combinations thereof, may be disposed between the line light source and the sheet. It is appropriate that the width of the excitation light emitted from the line light source on the sheet is 10 to 4000 μm.

Also, in order to increase the weekly efficiency of the stimulating light emitted from each part of the sheet in the line sensor, the object surface and the image surface are constituted by an image forming system corresponding one-to-one. It is desirable to arrange a gradient index lens array such as a selfoc lens array or a rod lens array, a cylindrical lens, a slit, an optical fiber bundle, or a combination thereof between the sheet and the line sensor.

The direction in which the line light source and the line sensor are moved relative to the stimulable phosphor sheet (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. It may be moved in a diagonal direction deviating from a direction substantially perpendicular to the direction, or may be moved in a zigzag manner with the moving direction changed.

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 further prevent the excitation light from entering the line sensor.

The line light source and the line sensor may be arranged on the same side of the sheet, or may be arranged separately on opposite sides of the sheet. 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.

Further, it is desirable that the power (corresponding to the irradiation intensity and the emission luminance) of the excitation light applied to the sheet does not fluctuate. If power fluctuations can occur, the amount of excitation light is monitored by the monitoring means, and based on the monitoring results, when power fluctuations occur, the light source (line light source is switched on) faster than the photoelectric conversion speed of the CCD. Including)
For example, the modulation means may modulate the drive voltage of the light source so that the light emission power (luminance) of the light source becomes constant, and the influence of the power fluctuation may be suppressed.

The line sensor may have a large number of CCDs arranged only in its length direction (long axis direction).
D is preferably provided. In this case, the plurality of CCDs is not limited to a matrix-like arrangement in which the CCDs are arranged in a straight line in any of the long axis direction and the short axis direction. An array arranged in a straight line in the long axis direction but arranged in a zigzag shape in the short axis direction, an array arranged in a straight line in the short axis direction but arranged in a zigzag shape in the long axis direction, and arranged in zigzag in both axis directions They may be arranged in an array.

In a configuration in which the number of CCDs is increased so as to be affected by the transfer rate, a memory element corresponding to each CCD is provided, and the charge accumulated in each CCD is temporarily stored in each memory element. The configuration may be such that the charge is read from each memory element during the next charge accumulation period, thereby avoiding a reduction in the charge accumulation time due to an increase in the charge transfer time.

Also, C in the long axis direction of the line sensor
It is desirable that the number of arranged CDs is 1000 or more, and the length of the line sensor is desirably longer than or equal to one side of the sheet on its light receiving surface. The sensor may be inclined with respect to the side of the sheet to perform photoelectric detection.

As the stimulable phosphor sheet for storing and recording the radiation image information, a normal stimulable phosphor sheet which serves both as a phosphor for absorbing radiation and a radiation energy, ie, a phosphor for storing radiation image information, is used. However, as proposed in Japanese Patent Application No. 11-372978, the radiation absorbing function and the energy storage function of the conventional stimulable phosphor are separated to provide a phosphor excellent in radiation absorption. Fluorescent materials with excellent responsiveness to stimulating luminescence are used for radiation absorption and radiation image information storage, respectively. A region is emitted, and this emitted light is absorbed by using the above-described phosphor having excellent responsiveness to stimulated emission (storage-dedicated phosphor), the energy is accumulated, and the light is excited by light in the visible to infrared region. The Energy is released as stimulated light, the use of the system for obtaining an image signal by reading the emitted light photoelectrically sequentially by photoelectric reading means, the detection quantum efficiency of radiation imaging, i.e. radiation absorptivity,
Since the stimulable luminous efficiency and the efficiency of taking out the stimulable luminescent light can be improved as a whole, the stimulable phosphor sheet targeted by the radiation image information reading apparatus of the present invention contains the phosphor dedicated to storage. It is preferable that

Here, the storage-dedicated phosphor absorbs light emitted from the radiation absorbing phosphor in the ultraviolet to visible region and accumulates its energy to produce image information. Since the light is emitted by the radiation absorbing phosphor by absorbing the radiation, the image information stored in the storage phosphor sheet is also radiation image information.

The image signal processing apparatus of the present invention further comprises a dark current (signal output from the CCD when there is no light incident on the CCD) correction processing and a sensitivity correction processing for the image signal output from the line sensor. (Process for correcting variations in sensitivity between CCDs), linearity correction, correction means for correcting shading caused by unevenness of excitation light and non-uniformity of the reading optical system, to further improve image quality. desirable.

[0027]

According to the radiographic image information reading apparatus of the present invention, double sampling is performed on an analog image signal in a linear region, and then A / D conversion is performed on a logarithmically converted signal. Therefore, since the minimum resolution of the image signal to be subjected to the A / D conversion is relatively high, a sufficient resolution can be achieved without increasing the number of bits of the A / D conversion. Therefore, an increase in the data amount can be suppressed, and the processing time can be reduced.

Further, according to the radiation image information reading apparatus of the present invention, the anti-aliasing filter can be applied to the analog image signal regardless of the special output characteristics of the CCD. Noise can be removed, and a high-quality image can be obtained.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image signal processing apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a configuration of a radiation image information reading apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view showing a cross section taken along line II of the radiation image information reading apparatus shown in FIG.
FIG. 3 is a diagram showing a detailed configuration of the line sensor 20 of the reading apparatus shown in FIGS.

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 line excitation) having a line width of about 100 μm.
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 set so as to reflect the excitation light L and transmit a stimulated emission light M described later, and a linear excitation light L reflected by the dichroic mirror 14 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 arranged, hereinafter referred to as a first Selfoc lens array) 15 for forming a parallel light beam, and the first Selfoc lens Is a parallel light flux by Zuarei 15, each CCD21 constituting the the dichroic mirror 14 emitted light M having passed through the line sensor 20 described below
SELFOC lens array for focusing light on a light receiving surface
16, an excitation light cut filter 17 which slightly 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 number of CCDs 21 for receiving the photostimulated light M transmitted through the excitation light cut filter 17 and performing photoelectric conversion are arranged.
A signal processing unit for sequentially reading the output from the CD 21 in accordance with the movement of the sheet 50 and performing a digitizing process as described later to obtain a digital image signal S3 representing the radiation image information accumulated and recorded on the sheet 50. 29 is provided.

The first selfoc lens array 15 has the function of forming, on the dichroic mirror 14, the emission area of the photostimulated light M on the sheet 50 as an image plane for forming an image with a one-to-one size. The second Selfoc lens array 16 is C
On the light receiving surface of the CD 21, the image of the stimulated emission light M on the dichroic mirror 14 serves as an image surface for forming a one-to-one image.

The optical system 12 including a collimator lens and a toric lens expands the laser beam L from the BLD 11 to a desired irradiation area on the dichroic mirror 14.

More specifically, as shown in FIG. 2, the line sensor 20 has a large number (for example, 1000 or more) of CCDs 21 arranged along the long axis direction (the arrow X direction in FIG. 1). Are arranged so as to be arranged in three rows in a zigzag manner in the conveying direction of the sheet 50 (the direction of the arrow Y). Each of the CCDs 21 constituting the line sensor 20 has a light receiving surface having a size of about 100 μm in length × 100 μm in width.
The size of the photostimulable emission light M emitted from a portion having a size of about 100 μm in length × 100 μm in width on the surface of the substrate is received.

The signal processing means 29 is provided for each C of the line sensor 20.
A reading unit 30 for reading an output from the CD 21 to obtain an analog image signal Q; a sampling unit 3 for performing a double correlation sampling process on the image signal Q to obtain an image signal S1
1. Logarithmic conversion means 32 for logarithmically converting image signal S1 to obtain logarithmically converted image signal S2, anti-aliasing filter 3 for removing high-frequency noise from image signal S2
3. An A / D converter 34 for digitizing the image signal S3 from which noise has been removed by the anti-aliasing filter 33 to obtain a digitally processed image signal S4.

Next, the operation of the radiation image information reading apparatus of this embodiment will be described.

First, as the scanning belt 40 moves in the direction of the arrow Y, the sheet 50 on which the radiation image information is stored and conveyed is conveyed 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 its vicinity, photostimulable emission light M having an intensity corresponding to the accumulated 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 CCDs 21. At this time, the excitation light L slightly reflected on the stimulated emission light M transmitted through the second selfoc lens array 16 and reflected on the surface of the sheet 50 is cut by the excitation light cut filter 17.

The line sensor 20 photoelectrically converts the stimulated emission light M received by each CCD 21, and an electric signal obtained by the photoelectric conversion is input to the reading means 30.

The reading means 30 reads the input electric signal and outputs the analog image signal Q obtained by reading to the sampling means 31. The sampling means 31 performs a double sampling process on the analog image signal Q to obtain a sampled image signal S1 and a logarithmic conversion means 32
Output to The image signal S1 is logarithmically converted by the logarithmic conversion means 32 to become a logarithmically converted image signal S2.
Output to the anti-aliasing filter 33. The high frequency noise is removed from the image signal S2 by the anti-aliasing filter 33 to become an image signal S3, which is output to the A / D conversion means 34. The A / D converter 34 outputs the image signal S3
Is subjected to a digitizing process to obtain a processed digital image signal S4.

As described above, according to the present embodiment, the analog image signal Q obtained by reading the output from each CCD 21 of the line sensor 20 is first subjected to double sampling processing by the sampling means 31 and then logarithmically processed. Since the A / D conversion is performed on the image signal S3 obtained by performing the conversion processing, without increasing the data amount at the time of the A / D conversion,
An image signal S4 having a sufficient resolution can be obtained.

Since the logarithmic conversion means 32 performs logarithmic conversion on the image signal after the double sampling processing, there is no need to provide a high-speed logarithmic conversion circuit, which is economical.

Before the A / D conversion in the A / D conversion means 34, the anti-aliasing filter 33 is applied to the image signal S1 which has been subjected to the double correlation sampling processing by the sampling means 31. Therefore, an image signal from which high frequency noise has been removed can be obtained.

Further, the radiation image information reading apparatus according to the above-described embodiment adopts a configuration in which the optical path of the excitation light L and the optical path of the stimulating light M partially overlap, thereby further reducing the size of the apparatus. However, the present invention is not limited to such a configuration. For example, as shown in FIG. 4, a configuration in which the optical path of the excitation light L and the optical path of the photostimulated light M do not overlap at all may be applied. it can.

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. And a photo-receiving surface of each CCD 21 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. Lens array 16 for focusing light, excitation light cut filter 17 for cutting excitation light L mixed with photostimulated luminescence light M incident on selfoc lens array 16, and transmitted through excitation light cut filter 17. A line sensor in which a large number of CCDs 21 are arranged to receive the photostimulated light M and perform photoelectric conversion.
20 and a signal processing means 29 for reading an output from each CCD 21 constituting the line sensor 20 to obtain an image signal S4.

In the radiation image information reading apparatus of each of the above-described embodiments, both the light source of the excitation light and the line sensor are arranged on the same surface of the sheet, and the stimulating light 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. 5, the excitation light source and the line sensor are arranged on different sides of the sheet, and the sheet surface on which the excitation light enters It is also possible to adopt a configuration of a transmitted light condensing type in which stimulated emission light emitted from the surface on the opposite side is received.

That is, in the illustrated radiation image information reading apparatus, the front end and the rear end of the stimulable phosphor sheet 50 (the front end and the rear end have no or no radiation image recorded thereon). The scanning belt 40 'supports the sheet in the direction of arrow Y while supporting the sheet, and emits the linear excitation light L from the BLD 11 and the BLD 11 which emits the linear excitation light L in a direction substantially perpendicular to the surface of the sheet 50. 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,
Irradiates 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 onto the light receiving surfaces of the CCDs 21 constituting the line sensor 20 described later. The SELFOC lens array 16, the exciting light cut filter 17 for cutting the exciting light L mixed in the exciting light M ′ incident on the SELFOC lens array 16, and the exciting light M ′ transmitted through the exciting light cut filter 17 The configuration includes a line sensor 20 in which a number of CCDs 21 that receive light and perform photoelectric conversion are arranged, and a signal processing unit 29 that reads an output from each of the CCDs 21 that form the line sensor 20 to obtain an image signal S4.

Further, as shown in FIG. 6, two line sensors are arranged on both sides of the sheet, using a stimulable phosphor sheet whose support is formed of a stimulable luminescent light transmissive material. It is also possible to adopt a double-sided reading type configuration in which stimulated emission light emitted from both sides of the sheet on which the excitation light is incident is received.

That is, the radiation image information reading apparatus shown in FIG. 6 is a scanning belt 4 that supports the front end and the rear end of the stimulable phosphor sheet 50 and conveys the sheet 50 in the arrow Y direction.
0 ′, a combination of a BLD 11 that emits the linear excitation light L toward the surface of the sheet 50, a collimator lens that collects the linear excitation light L emitted from the BLD 11, and a toric lens that expands the beam only in one direction An optical system 12, a dichroic mirror 14, and a dichroic mirror 14 arranged at an angle of 45 degrees with respect to the surface of the sheet 50 and set so as to reflect the excitation light L and transmit the stimulating light M described later. The linear excitation light L reflected by the light is condensed on the sheet 50 into a linear shape extending along the arrow X direction, and the linear excitation light L is condensed and emitted from the sheet 50. Selfoc lens array 15 that makes stimulated emission light M according to the obtained radiation image information a parallel light flux, and brightness emitted from the surface of sheet 50 (the surface irradiated with excitation light L) and transmitted through dichroic mirror 14. Line sensor emitted light M
The SELFOC lens array 16a and the SELFOC lens array 16a that condense light on the light receiving surface of each CCD 21a constituting the 20a
Excitation light cut filter 17a, Excitation light cut filter 17a for cutting the excitation light L mixed in the stimulating light M transmitted through
Sensor 20a in which a number of CCDs 21a are arranged to receive the photostimulated light M transmitted through and photoelectrically convert the light M.
The signal processing means 29a for obtaining an image signal S4a representing the radiation image information stored and recorded on the sheet 50 by sequentially reading the output from each CCD 21a constituting the sheet 20a according to the movement of the sheet 50, Stimulated emission light M 'emitted from the surface opposite to the side irradiated with the excitation light L)
Lens array 16b for condensing the light on the light receiving surface of each CCD 21b constituting the line sensor 20b, and an excitation light cut filter for cutting the excitation light L mixed with the stimulated emission light M 'transmitted through the selfoc lens array 16b 17b, a line sensor 20b in which a large number of CCDs 21b for receiving the photostimulated light M 'transmitted through the excitation light cut filter 17b and performing photoelectric conversion are arranged, and each CC constituting the line sensor 20b.
A signal processing means 29b is provided which obtains an image signal S5b representing radiation image information stored and recorded on the sheet 50 by sequentially reading the output from D21b according to the movement of the sheet 50.

In the embodiment shown in FIGS. 4 to 6, the same effects as those in the embodiment shown in FIGS. 1 and 2 can be obtained.

In each of the above embodiments, the radiation image is read by moving the stimulable phosphor sheet with respect to the line light source and the line sensor. May be read to read the radiation image.

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, A line sensor and various known configurations can be employed. In addition, the image processing apparatus further includes an image processing device that performs various types of image processing on the signal output from the signal processing unit, and further includes an erasing unit that appropriately emits radiation energy still remaining on the sheet whose excitation has been completed. It is also possible to adopt a configuration that is different from that of the first embodiment.

Further, the stimulable phosphor sheet for radiation energy subtraction is also used as a phosphor sheet having a structure subdivided into a number of microcells by, for example, an excitation light reflecting partition member extending in the thickness direction of the phosphor sheet. For example, a so-called anisotropic phosphor sheet can be used.

The radiation image reading apparatus according to the present invention, as a stimulable phosphor sheet, can absorb light in the ultraviolet to visible region and store its energy, and can be excited by light in the visible to infrared region. It is also possible to use a phosphor containing a stimulable phosphor that can emit energy as stimulating light.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of the radiation image information reading apparatus shown in FIG.
Sectional view showing a line section

FIG. 3 is a diagram showing details of a line sensor of the radiation image information reading apparatus shown in FIGS. 1 and 2;

FIG. 4 is a configuration diagram showing another embodiment of the radiation image information reading apparatus according to the present invention (part 1);

FIG. 5 is a configuration diagram illustrating another embodiment of the radiation image information reading apparatus according to the present invention (part 2);

FIG. 6 is a configuration diagram showing another embodiment of the radiation image information reading apparatus according to the present invention (part 3).

FIG. 7 is a diagram for explaining output characteristics of a CCD;

[Explanation of symbols]

Reference Signs List 11 Broad area laser (BLD) 12 Optical system composed of collimator lens and toric lens 14 Dichroic mirror 15, 16 Selfox lens array 17 Excitation light cut filter 20 Line sensor 21 CCD 29 Signal processing means 30 Reading means 31 Sampling means 32 Logarithmic conversion Means 33 Anti-aliasing filter 34 A / D conversion means 40 Scanning belt 50 Storage phosphor sheet L Excitation light M Stimulated emission light

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) H04N 5/321 H04N 1/04 EF term (Reference) 2G083 AA03 BB05 CC10 EE02 EE10 2H013 AC06 AC11 5B047 AA17 BA01 BB02 BC05 BC09 5C024 AX17 CX00 CX03 EX01 EX04 EX41 EX42 GY01 HX00 HX04 HX13 HX23 5C072 DA02 DA09 EA05 NA01 NA04 NA08 UA06 UA09 VA01

Claims (2)

[Claims] 1. A line light source for irradiating a part of a stimulable phosphor sheet storing radiation image information with excitation light in a linear manner, and a part irradiated on a part of the sheet or a part irradiated with the excitation light. A line sensor comprising a plurality of CCDs arranged in the length direction of the portion for receiving photostimulated light emitted from the back side of the corresponding sheet and performing photoelectric conversion, and the line light source and the line sensor Scanning means for moving the radiation image information relative to the sheet in a direction different from the length direction, and sequentially reading outputs from the CCDs of the line sensor in accordance with the movement, thereby obtaining the radiation image information. A radiation image information reading apparatus comprising: reading means for obtaining an analog image signal representing the image signal; a sampling means for performing a double correlation sampling process on the analog image signal; A logarithmic conversion means for the double sampling image signals to logarithmic conversion, and A / D conversion with respect to the logarithmic converted image signal,
A radiation image information reading apparatus comprising: A / D conversion means for obtaining a digital image signal. 2. An anti-aliasing filter for performing anti-aliasing filter processing before performing A / D conversion on the image signal that has been subjected to the double sampling processing. 2. The radiation image information reading device according to 1.