JP2007218719A - Marker for position detection, radiation image conversion panel equipped with such marker and radiation image acquisition system using such panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a correction marker for a radiation image conversion panel, the radiation image conversion panel and a radiation image acquisition system that enable the identification of a position in the radiation image conversion panel where a radiation image is acquired to thereby make it possible to acquire high-quality radiation images from which influences of point defects caused by nonuniform evaporation of phosphors and the like and irregular luminescence of accelerated phosphorescence light are removed more accurately. <P>SOLUTION: A part of the radiation image conversion panel 1 including a recording layer made of storage phosphors is provided with the correction marker 2. The marker 2 is composed of phosphors and has an optically steep edge. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technical field of a radiation image conversion panel and a radiation image acquisition system that generate stimulated emission light upon irradiation with excitation light, and more specifically, a marker for detecting a position of a recorded radiation image, The present invention relates to a radiation image conversion panel provided with a position detection marker and a radiation image acquisition system using the radiation image conversion panel.

  Conventionally, when a radiation such as X-rays is irradiated, a part of this radiation energy is accumulated, and then when an excitation light such as visible light is irradiated, a stimulable phosphor (stimulated phosphor) that exhibits stimulated luminescence according to the accumulated radiation energy. A radiation image of a subject such as a human body is temporarily recorded as a latent image on the stimulable phosphor layer, and the stimulable phosphor layer is irradiated with excitation light such as laser light. A radiographic image recording / reproducing system including a radiographic image recording apparatus and a radiographic image reading apparatus that generates luminescent light and photoelectrically detects the stimulated luminescent light to acquire an image signal representing a radiographic image of a subject is disclosed. Radiography) system.

  As a recording medium used in this radiographic image recording / reproducing system, a radiographic image conversion panel prepared by laminating a stimulable phosphor layer on a substrate is used. When the radiation image conversion panel is irradiated with erasing light, the residual radiation energy is released and the radiation image can be recorded again, and can be used repeatedly.

Further, as the radiation image reading device, for example, a line sensor that detects the stimulated emission light generated from the radiation image conversion panel upon irradiation with linear excitation light, and the line sensor with respect to the radiation image conversion panel. A transfer means for transferring in a direction orthogonal to the linear direction, and receiving a linear excitation light irradiation while transferring the line sensor relative to the radiation image conversion panel. There is known an apparatus for detecting a photostimulated luminescence generated from a conversion panel and acquiring a radiation image.
The radiographic image acquired as described above is subjected to shading correction or the like that removes the influence of uneven emission of the stimulated emission light, and is recorded on a film as a visible image or displayed on a high-definition CRT. Provided for diagnosis.

  As a technique related to shading correction used here, for example, a radiation image read from a radiation image conversion panel (that is, correction exposure) (ie, correction exposure). Radiological image) is stored in the apparatus in advance, and then a radiographic image (that is, a radiographic image of the subject) read from the radiographic image conversion panel in which the radiation is blown through the subject is obtained, and the correction is performed from the radiographic image of the subject. It is known that a radiographic image is subtracted to obtain a radiographic image (corrected radiographic image) from which the influence of shading is removed (see, for example, Patent Document 1, Patent Document 2, etc.).

  However, these techniques do not consider variations in the arrangement position of the radiation image conversion panel on the apparatus in the radiation image recording apparatus and the radiation image reading apparatus when the correction radiation image is recorded. However, there has been a problem that correction regarding misalignment error is not made.

For this problem, the applicant previously proposed in Japanese Patent Application No. 2002-279248 “Radiation image acquisition method and apparatus” (see Japanese Patent Application Laid-Open No. 2004-117684 (hereinafter referred to as Patent Document 3)). A technique for correcting the position related to the shading correction is proposed.
In this technology, a light emitting marker that specifies the position on the radiation image conversion panel is arranged outside the main image area of the radiation image conversion panel, and the position of the radiation image conversion panel itself is specified by reading the position of this position light emission marker. It is what you do.

  That is, in the technique disclosed in Patent Document 3, first, the idea of correcting the transfer position deviation of the radiation image conversion panel at the time of recording is performed, and after this is achieved, predetermined correction (various misalignment related to the position deviation is performed). Correction). In this technology, a light emitting marker that identifies the position on the radiation image conversion panel is placed outside the main image area of the radiation image conversion panel, which makes the correction operation easier and more accurate than previous technologies. The certainty of the result can be obtained.

  By the way, the radiation image conversion panel used in the above-described radiation image recording / reproducing system is a panel in which a phosphor sheet formed by a method such as vapor deposition is used to form the above-described stimulable phosphor layer on a support. is there. What is necessary for this radiation image conversion panel is that there is no structural defect caused by uneven deposition of phosphors in the above-described deposition process. Of course, if this defect is minor, the diagnosis will not be affected, but a defect of a certain level or more will affect the diagnosis. Regarding the use of the radiation image conversion panel having such a defect, it It is necessary to take measures against

JP 2000-013599 A Japanese Patent Application Laid-Open No. 01-086759 JP 2004-117684 A

  The present invention further improves the technique disclosed in Patent Document 3 above, and makes it possible to specify the position in the radiation image conversion panel from which the radiation image is acquired, thereby causing point defects caused by uneven deposition of phosphors, etc. The purpose of the present invention is to provide a radiation image conversion panel and a radiation image acquisition system that can acquire a high-quality radiation image that more accurately eliminates the influence of light emission unevenness of the photostimulated luminescence light. is there.

  Another object of the present invention is to provide a recorded radiation image position detection marker suitable for use in the radiation image conversion panel (the position information detected by this marker is influenced by the uneven emission of the stimulated emission light). In the following, this marker will be referred to as a correction marker), and its position detection accuracy is further improved.

  In order to achieve the above-described object, the correction marker according to the present invention is configured by a phosphor provided in a part of a radiation image conversion panel including a recording layer made of a stimulable phosphor (first stimulable phosphor). The position detection correction marker is characterized by having an optically steep edge portion (claim 1).

Here, in the correction marker according to the present invention, the optically steep edge portion may be formed by covering the phosphor constituting the correction marker with a light shielding material having an opening. Preferred (claim 2).
Further, the optically steep edge portion is formed by cutting the phosphor constituting the correction marker from a sheet-like one and pasting it on a part of the radiation image conversion panel. (Claim 3).
Further, the optically steep edge portion may be formed by forming the phosphor constituting the correction marker in a recess formed in a part of the radiation image conversion panel. Preferred (claim 4).

Preferably, the optically steep edge portion is formed by disposing the phosphor constituting the correction marker on a light shielding material having an opening.
Still further, it is preferable that the correction marker according to the present invention has a surface covered with an optically transparent sealing material.

Further, the radiation image conversion panel according to the present invention is a radiation image conversion panel including a recording layer made of a stimulable phosphor, and a part of the radiation image conversion panel is formed of a phosphor. 6. The correction marker according to claim 6 is provided (claim 7).
Here, in the radiation image conversion panel according to the present invention, it is preferable that the correction marker is provided outside an image recording area (image area) of the radiation image conversion panel.

Further, as the phosphor constituting the correction marker, the stimulable phosphor that emits light having a wavelength shorter than the wavelength of the secondary excitation light with respect to the stimulable phosphor (first stimulable phosphor) constituting the recording layer. It is preferable to use (second accumulating phosphor) (claim 9).
Further, as the stimulable phosphor constituting the correction marker, light capable of erasing energy accumulated in the stimulable phosphor (first stimulable phosphor) constituting the recording layer as primary excitation light. It is preferable to use light that can secondarily excite the first stimulable phosphor as the secondary excitation light.

  In addition, the radiation image acquisition system according to the present invention uses the above-described radiation image conversion panel, and receives a primary excitation light to form a storage phosphor (first structure) that constitutes the recording layer on the radiation image conversion panel. Radiation image recorded as a latent image on the radiation image conversion panel by receiving through the imaging optical system the stimulated emission light generated from the storage phosphor and the emission light generated from the phosphor on the correction marker And a detecting means for acquiring an image signal representing the position of the image of the correction marker recorded in the correction marker, and the radiation image represented by the image signal based on the position of the image of the correction marker represented by the image signal. Light emission unevenness correcting means for acquiring an image signal representing a radiation image from which the influence of light emission unevenness of the stimulated emission light is removed using the position-corrected image signal after correcting the position; Characterized by comprising (claim 11).

  Here, the point defect caused by the phosphor deposition unevenness is a non-light emitting region due to the local lack of the phosphor, and the emission of the stimulated emission light also caused by the phosphor deposition unevenness or the like. The unevenness means unevenness of the light intensity of the stimulated emission light caused by the difference in the emission characteristics depending on the position of the radiation image conversion panel.

  According to the present invention, when the correction marker to be added to the radiation image conversion panel is formed of a phosphor, the influence of sagging (edge dullness) in the edge portion of the phosphor constituting the correction marker is removed and optically By using sharp edges, the position detection accuracy can be further improved, and the detection accuracy of structural defects by the radiation image conversion panel using this correction marker and the effect of removing the influence are improved. It can be greatly improved.

  Further, in the present invention, position information is accumulated in the correction marker by first exciting with the primary excitation light for the stimulable phosphor constituting the recording layer (so-called primary excitation). Corresponds to the position information at the time of excitation for reading by secondary excitation light after image recording on the storage phosphor constituting the recording layer (corresponding to second excitation for the phosphor constituting the correction marker). The emission wavelength of the stimulable phosphor that constitutes the recording layer is obtained by emitting the emitted light and acquiring the image signal indicating the radiation image from which the influence of the positional deviation of the radiation image conversion panel is removed based on this. The light emitting marker emits light in a region close to, and it is possible to obtain a higher quality radiation image from which the influence of the structural defect included in the radiation image conversion panel is removed.

  Still further, as the stimulable phosphor constituting the correction marker, light capable of erasing energy accumulated in the stimulable phosphor (first stimulable phosphor) constituting the recording layer as primary excitation light. Is used as the secondary excitation light, so that the light that can secondarily excite the first stimulable phosphor is used, and the erasing light of the stimulable phosphor constituting the recording layer constitutes a correction marker. It can be used as the excitation light of the stimulable phosphor, and the above-described effects can be obtained with a simple system configuration.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing a schematic configuration of a radiation image conversion panel according to an embodiment of the present invention. FIG. 2 is a plan view and a side view showing a schematic configuration of a radiation image reading apparatus that reads a radiation image from the radiation image conversion panel. 3 is a cross-sectional view showing an internal configuration of a reading unit in which a light source and a line sensor are integrally provided, FIG. 4 is a side view showing a state in which a radiation image conversion panel is positioned at a radiation image recording position, and FIG. Is a side view showing a state in which the radiation image conversion panel is positioned at the radiation image reading position, and FIGS. 6 to 8 are flowcharts for explaining the radiation image reading position deviation correction operation using the radiation image conversion panel according to the present embodiment. 9 and 10 are graphs related to image data processing.

  As shown in FIG. 1, the radiation image conversion panel 1 according to the present embodiment is located outside the main image recording area (hereinafter simply referred to as an image area) 1A (that is, outside the image area) of the radiation image conversion panel 1. Are provided with correction markers 2A, 2B,... For position detection that generate light that can be transmitted through an excitation light cut filter described later.

  Here, as an example, a case where a plurality of correction markers 2A, 2B,... Are provided is shown, but in the following description, only one correction marker is provided in order to simplify the explanation of the operation. I will explain that it is.

In the illustrated example, as a preferred example, the stimulable phosphor layer forming the image region of the radiation image conversion panel 1 is composed of cesium bromide (CsBr) serving as a phosphor component and europium bromide serving as an activator component. (EuBr _x (x is usually 2 to 3, particularly 2 is preferable) as a film forming material, and binary vacuum deposition by resistance heating is performed to form a storage phosphor on a supporting substrate. A phosphor formed of CsBr: Eu is used.

In addition, as the stimulable phosphor constituting the correction marker, here, information is obtained from light of a cold cathode fluorescent lamp (white, including 400 nm light) used as erasing light for the stimulable phosphor CsBr: Eu. Can be recorded, and light having a wavelength of 660 nm used as the secondary excitation light for the above-described stimulable phosphor CsBr: Eu is used as the secondary excitation light, and light having a shorter wavelength (about 400 nm to 600 nm, A phosphor layer made of Sr ₄ Al ₁₄ O ₂₅ : Eu, Sm that emits light at a peak of about 500 nm is used.

  The stimulable phosphor layer forming the image area or the stimulable phosphor layer constituting the correction marker may be other than the above as long as it has predetermined characteristics (excitation wavelength, emission wavelength, etc.). Needless to say, it may be formed.

  The above-described correction marker (hereinafter represented by the correction marker 2A) is formed separately from the radiation image conversion panel 1 formed of a phosphor sheet made of a stimulable phosphor layer that forms an image region. The corrected marker phosphor sheet can be produced and arranged by a method such as cutting and pasting it into a predetermined shape outside the image area.

  The correction marker 2A is used when the radiation image conversion panel 1 is read by a plurality of line scanners when inspecting the presence or absence of a structural defect on a stimulable phosphor layer, which will be described later, and the number and arrangement of line scanners to be used. It is necessary to form it according to the pitch or the like. Thereby, the presence position of the structural defect which exists in the image area | region of the radiation image conversion panel 1 can be read efficiently and correctly.

A radiation image reading apparatus that reads a radiation image from the radiation image conversion panel 1 will be described with reference to FIGS. 2 (a), 2 (b) and FIG.
In the figure, 10 is a light source that emits linear excitation light, 30 is an image signal indicating a radiation image by receiving and photoelectrically converting stimulated emission light generated from the radiation image conversion panel 1 upon irradiation with excitation light. A line sensor 70, which is a detection means to acquire, indicates a panel base moving unit that switches the radiation image conversion panel 1 between the radiation image recording position W and the radiation image reading position R.

  Reference numeral 75 denotes a reading unit 50 in which the light source 10 and the line sensor 30 are integrally disposed, and a direction (hereinafter referred to as sub-scanning) orthogonal to the linear direction (hereinafter referred to as main scanning direction (X direction)). A linear slide system 60 that moves in a direction (referred to as a Y direction) is a data processing means 60 such as a function for converting the image signal acquired by the line sensor 30 into image data consisting of digital values and discriminating the structural defects described above. An image data processing unit is shown.

  The light source 10 is a broad area laser 11 that emits linear excitation light, and the excitation light emitted from the broad area laser 11 is transmitted in the main scanning X direction on the radiation image conversion panel 1 via a reflection mirror 13 (described later) (see FIG. 3, the optical system 12 composed of a toric lens or the like that collects light in a linear region F extending in a direction perpendicular to the paper surface in FIG. 3, and the linear excitation light emitted through the optical system 12 to reflect the excitation light. The reflecting mirror 13 is used to change the optical path.

  The line sensor 30 includes an imaging lens 31, an excitation light cut filter 32, and a CCD element 33. The imaging lens 31 has a large number of lenses arranged in the main scanning X direction and is irradiated with the linear excitation light. A linear region F on the image conversion panel 1 is imaged on the CCD element 33. The CCD element 33 has a large number of light receiving portions (photoelectric conversion elements) arranged in the main scanning X direction, and detects the stimulated emission light generated from the linear region F imaged by the imaging lens 31. The excitation light cut filter 32 is inserted between the imaging lens 31 and the CCD element 33 to block excitation light mixed in the stimulated emission light generated from the radiation image conversion panel 1 and transmit the stimulated emission light.

  The light source 10 and the line sensor 30 are integrally provided in a reading unit 50. The reading unit 50 receives a radiographic image from the radiographic image conversion panel 1 in addition to the light source 10 and the line sensor 30. An erasing fluorescent lamp 39 extending in the main scanning X direction for irradiating the radiation image conversion panel 1 with erasing light for erasing radiation energy remaining in the radiation image conversion panel 1 after being read is provided.

  The light source 10, the line sensor 30 and the erasing fluorescent lamp 39 have a width (length in the X direction) corresponding to the image area of the radiation image conversion panel 1, and will be described later. During scanning for erasing operation, the correction marker 2A can be uniformly exposed (excited) by the erasing fluorescent lamp 39, and the position of the correction marker 2A can be read at the time of image reading from the image area of the radiation image conversion panel 1.

  The panel base moving unit 70 is opposite to the panel base 71 for fixing the radiation image conversion panel 1 so that the radiation image conversion panel 1 stands substantially vertically, and the side of the panel base 71 on the side of the radiation image conversion panel 1. The panel base 71 is held via the side, and the panel base 71 is translated in a direction perpendicular to the surface S of the radiographic image conversion panel 1 (in the direction of arrow Z in the figure). And a cylinder expansion / contraction drive mechanism 72 that switches between the radiation image recording position W and the radiation image reading position R. The panel base moving unit 70 is fixed on the apparatus base 80.

  The linear slide system 75 is arranged on both sides of the panel base 71 in the sub-scanning Y direction so as not to interfere with the movement of the panel base 71, and is fixed to the apparatus base 80. The guide rails 77A and 77B are arranged on the rail base bases 76A and 76B, respectively, and extend in the sub-scanning Y direction, hold the reading unit 50, and are guided by the guide rails 77A and 77B and driven by driving means (not shown). It comprises a reading unit moving table 78 moved in the sub-scanning Y direction.

  The image data processing unit 60 converts an image signal acquired by the line sensor 30 from an analog signal into a digital signal, and temporarily converts the image data converted into a digital signal by the A / D converter 61. Correction for storing correction image data indicating a radiation image (correction radiation image) representing the position of the structural defect acquired from the image buffer 62 to be stored and the radiation image conversion panel 1 uniformly irradiated with radiation. For image memory 63.

  The image data processing unit 60 also stores a subject image memory that stores subject image data indicating a radiation image (subject radiation image) of a subject including a structural defect acquired from the radiation image conversion panel 1 in which radiation has been blown through the subject. 64, and correction image data is input from the correction image memory 63 and subject image data is input from the subject image memory 64, and the positions of the correction markers 2A represented by both image data are corrected. A correction calculation unit 65 that subtracts the correction image data from the subject image data to execute structural defect correction, and acquires corrected image data indicating the corrected radiographic image (corrected radiographic image). .

  Next, with respect to the operation in the above embodiment, FIG. 6 (operation for acquiring a correction radiation image), FIG. 7 (operation for acquiring a subject radiation image including a structural defect (Part 1)), and FIG. 8 (Subject radiation including a structural defect) The operation will be described with reference to an operation flowchart shown in (Image acquisition operation (part 2)).

First, a case where a correction radiation image for detecting the position where a structural defect exists is acquired will be described (see FIG. 6).
Here, it is assumed that the radiation image reading apparatus is in a state where an erasing process is performed after the previous X-ray imaging / image reading (step S66 described later). Accordingly, the radiation image conversion panel 1 is in a standby state for excitation (exposure / imaging) by X-rays, and the correction marker 2A is in an excited state (image recorded).

  The panel base moving unit 70 moves the panel base 71 to the side opposite to the apparatus base 80 side (+ Z direction in FIG. 2), thereby positioning the radiation image conversion panel 1 at the radiation image recording position W (FIG. 4). At this position, radiation Xe is uniformly blown onto the radiation image conversion panel 1 without passing through the subject, and a radiation image (hereinafter referred to as a uniform exposure image) is recorded (step S61). At this time, the reading unit 50 is located at the retracted position P1 on the rail base base 76B side.

  After the recording of the uniform exposure image on the radiation image conversion panel 1 is completed, the panel base moving unit 70 moves the panel base 71 to the apparatus base 80 side (the −Z direction in the drawing), The radiation image conversion panel 1 is moved to the radiation image reading position R, and the uniform exposure image recorded on the radiation image conversion panel 1 and the position (image) of the correction marker 2A are read at this position. That is, the reading unit 50 is moved by the linear slide system 75, and the reading unit 50 is positioned at the reading start position P2 on the radiation image conversion panel 1. While the reading unit 50 is moved from the rail base base 76B side to the rail base base 76A side (in the direction of arrow D1 in FIG. 5) by the linear slide system 75, the linear excitation light Le is emitted from the light source 10 by the reading unit 50. The stimulated emission light generated from the radiation image conversion panel 1 upon receiving the linear excitation light Le is received by the CCD element 33 through the excitation light cut filter 32, and A / D converted to the radiation. Image data indicating the uniform exposure image recorded on the image conversion panel 1 is acquired (step S62) (see FIG. 5).

  By subtracting the reference bias data indicating a certain luminance uniformly from the image data, the correction image data indicating the correction radiation image is obtained and stored in the correction image memory 63 (step S63).

  At this time, the light generated from the correction marker 2A that has been irradiated with the linear excitation light Le from the light source 10 is read through the excitation light cut filter 32, and this data is sent to the image data processing unit 60. Here, the position of the correction marker 2A is calculated using an algorithm which will be described later (step S64). Data on the position of the correction marker 2A is also stored in the correction image memory 63 (step S65).

  The correction image data and the position data are sequentially stored in the correction image memory 63 through the A / D converter 61 and the image buffer 62 for each line in the main scanning X direction. When the reading unit 50 is moved to the end position P3 on the rail base base 76A side, reading of the radiation image recorded on the radiation image conversion panel 1 is completed, and the correction image data indicating the correction radiation image is corrected. Stored in the memory 63.

  Thereafter, the erasing fluorescent lamp 39 disposed in the reading unit 50 located at the end position P3 moves together with the reading unit 50 toward the rail base base 76B (in the direction of arrow D2 in FIG. 5). While being erased, the radiation image conversion panel 1 is irradiated with erasing light, and the radiation energy remaining in the radiation image conversion panel 1 is erased (step S66). Thereby, the radiographic image conversion panel 1 can record the radiographic image again. The correction marker 2A is excited (image recorded) by the fluorescent lamp.

  Next, a case where a subject radiation image (actual image) is acquired will be described (see FIGS. 7 and 8).

  In this case as well, the radiation image reading apparatus is in a state where the erasing process is performed after the previous X-ray imaging / image reading execution, and the radiation image conversion panel 1 is excited by X-rays (exposure / imaging). In the standby state, the correction marker 2A is in an excited (image recorded) state.

  The panel base moving unit 70 moves the panel base 71 in the + Z direction to position the radiation image conversion panel 1 at the radiation image recording position W (see FIG. 4). The radiation Xe is blown off and a radiation image of the subject 5 is recorded on the radiation image conversion panel 1 (step S71).

  After the recording of the radiographic image of the subject 5 on the radiographic image conversion panel 1 is finished, the panel base moving unit 70 moves the panel base 71 in the −Z direction to move the radiographic image conversion panel 1 to the radiographic image reading position. In this position, the radiographic image recorded on the radiographic image conversion panel 1 is read (step S72), and image data indicating the radiographic image of the subject 5 recorded on the radiographic image conversion panel 1 is read. That is, subject image data indicating a subject radiation image is acquired. This subject image data is stored in the subject image memory 64 through the A / D converter 61 and the image buffer 62 (step S73).

  At this time, the light generated by the irradiation of the excitation light Le is transmitted through the excitation light cut filter 32 from the correction marker 2A disposed on the radiation image conversion panel 1, and is read from the data. In this way, the position of the correction marker 2A is calculated (step S74). Data on the position of the correction marker 2A is also stored in the correction image memory 63 (step S75).

  Thereafter, the correction calculation unit 65 inputs the correction image data from the correction image memory 63 and also inputs the subject image data from the subject image memory 64, and the radiation image conversion panel 1 is converted from the data at the position of the correction marker 2A. After correcting the positions of the two image data, the subject image data is subjected to a process of subtracting the influence of the structural defect based on the correction image data to obtain corrected image data G indicating the processed radiation image And output (step S76). The details will be described later.

  After that, the erasing fluorescent lamp 39 disposed in the reading unit 50 located at the end position P3 moves toward the rail base base 76B together with the reading unit 50 (in the direction of arrow D2 in FIG. 5). ) Erasing light is irradiated toward the radiation image conversion panel 1 while being moved, and the radiation energy remaining in the radiation image conversion panel 1 is erased (step S77). Thereby, the radiographic image conversion panel 1 can record the radiographic image again. The correction marker 2A is excited (image recorded) by the fluorescent lamp.

  Here, the details of the image data correction processing performed by the correction calculation unit 65 will be described in detail (see FIGS. 8 to 10).

  FIG. 8 shows an outline of the image data correction processing performed by the correction calculation unit 65. FIG. 8A illustrates the case where the radiation image conversion panel 1 and the correction marker 2A are excited and then irradiated with uniform X-rays. When an image is formed on the radiation image conversion panel 1 and irradiated with excitation light for reading, and after the radiation image conversion panel 1 and the correction marker 2A are excited, an image by X-rays transmitted through the subject is formed. The image reading procedure of the correction marker 2A when the excitation light for reading is irradiated is shown.

  Note that the image reading procedure of the image area of the radiation image conversion panel 1 in the above two cases is not different from the normal image reading procedure. FIG. 8B shows a processing procedure for determining the position of the correction marker 2A on the radiation image conversion panel 1 by combining the image reading of the correction marker 2A in (a) in the above two cases. .

  FIGS. 9A and 9B show images formed in the image area on the radiation image conversion panel 1. First, FIG. 9A shows structural defects (3A, 3b, 3C,...) Existing in the image area of the radiation image conversion panel 1. Note that the above-described structural defects (3A, 3b, 3C,...) Are included in the X-ray image 1B transmitted through the subject shown in FIG.

  In the image data correction process performed by the correction calculation unit 65, first, an erasure process is performed, the radiation image conversion panel 1 is in an X-ray excitation (exposure / imaging) standby state, and the correction marker 2A is in an image recorded state. At some point, uniform X-ray irradiation is performed to form a so-called uniform image on the radiation image conversion panel 1. In this case, no change occurs in the energy state of the correction marker 2A.

  Next, as shown in FIG. 8A, an image formed in the image area of the radiation image conversion panel 1 described above and an image previously formed on the correction marker 2A are irradiated with predetermined excitation light. Read. Step S81 is a step of reading the image of the correction marker 2A (which corresponds to reading of the correction image).

In steps S82 and 83, processing for determining the position of the correction marker 2A is performed by the procedure shown in FIG. 10 using the image of the correction marker 2A read in step S81.
That is, first, as shown in FIG. 10A, the correction marker 2A is scanned in each of the X and Y directions of the correction marker 2A to measure the density, and the profile in each of the X and Y directions (FIG. 10). (B) and (c) are acquired, and for example, the position of the correction marker 2A (the center point in FIG. 10A) is determined based on the center position coordinate.

  Similarly, after the erasing process, when the radiation image conversion panel 1 is in a standby state for excitation (exposure / imaging) with X-rays, an image with X-rays transmitted through the subject is formed. As described above, in this case, the correction marker 2A does not change.

Next, in the same manner as described above, predetermined excitation light is irradiated to read the image shown in FIG. 8A and the image previously formed on the correction marker 2A (step S81). .
Further, in the same manner as before, the position of the correction marker 2A is determined by the procedure as shown in FIG. 10 using the image of the correction marker 2A read in step S81 (steps S82 and 83).

Next, the positioning error of the radiation image conversion panel 1 in these two X-ray imaging is obtained. This may be calculated based on the position of the correction marker 2A in the acquired image determined by the above method, as shown in step S84 of FIG. 8B.
Then, based on the amount of displacement obtained here, the position of the image in the image area of the radiation image conversion panel 1 is corrected, the correction image is subtracted from the image in the image area, and the image is included in the radiation image conversion panel 1. Structural defects are removed from the image in the image area.

Since the correction marker 2A always indicates the same position in the radiation image conversion panel 1, the attachment (arrangement) position of the radiation image conversion panel 1 to the radiation image recording / reading apparatus (ie, the radiation image conversion panel 1 and the line) Even when the relative position with respect to the sensor 30 fluctuates, the deviation amount with respect to the correct position can be obtained correctly.
The above is the description of the procedure for removing the influence (a kind of noise) of the radiation image conversion panel 1 including the structural defect and acquiring the high-quality image using the radiation image reading apparatus according to the present embodiment. .

  The above procedure is shown as an example of the present invention, and the present invention is not limited to this. For example, the algorithm for specifying the position from the image of the correction marker is not limited to the algorithm described above, and various algorithms exemplified below can be used.

First, as a method similar to the above-described example, there is a method in which an average value (intermediate value) between the density of the background portion and the density of the correction marker portion is obtained and the center of this intermediate value area is set as the marker position. .
Further, there is a method in which a sudden change in the differential value of density at the boundary portion between the background portion and the marker portion is captured, and the middle of the two is used as the marker position.

By the way, in the edge part of the above-mentioned correction marker composed of the second stimulable phosphor, depending on the forming method, there is a case where some sagging (edge dullness: details will be described later) may occur. is there. Therefore, it is preferable to improve the position detection accuracy by reducing the sagging as much as possible and making the edge portion of the correction marker an optically sharp edge.
A specific example will be described below.

FIG. 11 shows an embodiment of a correction marker that prevents the formation of sagging at the edge portion as described above.
In FIG. 11, (a) is a top view of the correction marker, and (b) is a cross-sectional view taken along line AA of (a).
In the correction marker 90 shown in FIG. 11, a phosphor layer 94 composed of the above-mentioned second stimulable phosphor is formed on a support 92 by a method such as printing, and the periphery thereof is formed in a frame shape made of a light shielding member. The filter is separated by a light shielding filter 96 and the upper surface thereof is covered with a transparent seal layer 98, and is configured to be attached to the peripheral portion of the radiation image conversion panel 1. Reference numeral 100 denotes an adhesive layer for attaching the correction marker 90 to the radiation image conversion panel 1.

  Here, the shape of the phosphor layer 94 shown in FIG. 11B is a peripheral portion thereof (in the illustrated example, a cross section from one direction is shown, but a cross section from a direction orthogonal thereto is substantially the same. However, in this specification, this is referred to as sagging. Needless to say, this sagging increases as the thickness of the phosphor layer 94 increases.

  For example, PET (polyethylene terephthalate) having a thickness of about 100 μm is used as the support 92 that constitutes the correction marker 90 described above, and the phosphor layer 94 is about 40 μm on the upper surface thereof as shown in FIG. A frame-shaped light-shielding filter 96 is also formed by printing on this, and transparent so as to prevent phosphors from scattering and foreign matter adhesion so as to cover this frame-shaped light-shielding filter 96. A seal layer 98 is attached.

  Here, the area of the phosphor layer 94 initially printed is (11 ± 0.1 mm) × so that the effective area of the phosphor layer 94 is (10 ± 0.1 mm) × (2 ± 0.1 mm). The shading filter 96 has an outer dimension of about (14 ± 0.1 mm) × (4 ± 0.1 mm), and the dimension of the window portion from which the phosphor is exposed is the above-mentioned. (10 ± 0.1 mm) × (2 ± 0.1 mm). The thickness of the light shielding filter 96 is 10 ± 4 μm as an example here.

Further, on the light shielding filter 96, a transparent sealing layer 98 made of an optically transparent PET sheet having a thickness of about 16 μm as an example is attached here. The transparent seal layer 98 is attached so as to cover not only the phosphor layer 94 but also the surrounding light shielding filter 96, thereby preventing the phosphor from scattering and preventing foreign matter from adhering.
Note that an adhesive layer 100 (such as an adhesive tape) for attaching the correction marker 90 to the radiation image conversion panel 1 is provided on the back surface of the support 92 of the correction marker 90 as shown in the illustrated example. Preferably it is.

Although exaggerated in FIG. 11B, the sagging 94a as described above is generated at the edge portion of the phosphor layer 94 formed by printing, and if used as it is for position correction by the correction marker as it is. There is a possibility that a position error due to this sagging will occur.
However, in the correction marker 90 according to the present embodiment, by covering the edge portion of the phosphor layer 94 with the light shielding filter 96, the thickness of the phosphor layer 94 at the substantial edge portion can be reduced. In the case of about 40 μm, the shading filter 96 is about 10 μm, so that the sagging of the edge portion becomes almost zero and the position error is substantially eliminated.

  FIG. 12 shows another embodiment of the correction marker that prevents the sagging at the edge portion. In the correction marker 90A according to the present embodiment, the phosphor layer 94b is not formed by printing, but a part of the phosphor layer previously formed into a sheet shape is cut to a predetermined size and pasted on the support 92. It is formed by. It should be noted here that when a part of the phosphor layer formed in a sheet shape is cut, the cut surface is cut as perpendicular to the surface as possible.

  The phosphor layer 94b formed as described above is cut so that the cut surface thereof is perpendicular to the surface. Therefore, the sagging as described above can be ignored, and the correction marker 90 described above can be ignored. There is an advantage that the light shielding filter 96 as provided is not necessary. The transparent seal layer 98 and the adhesive layer 100 on the back surface that are formed so as to cover the correction marker 90A including the phosphor layer 94b are the same as those in the previous embodiment.

  FIG. 13 shows still another embodiment of the correction marker that prevents the formation of sagging at the edge portion. In the correction marker 90B according to the present embodiment, the phosphor layer 94c is not formed on the support by printing, but the recess 92b is formed in the support 92a in advance, and the sheet is formed in the recess 92b. A part of the phosphor layer thus formed is cut into a predetermined size and fitted. It should be noted here that when a part of the phosphor layer formed in a sheet shape is cut, the cut surface is cut as perpendicular to the surface as possible.

  The phosphor layer 94c formed as described above is cut so that the cut surface thereof is perpendicular to the surface. Therefore, the sagging as described above can be ignored, and the correction marker 90 described above can be ignored. There is an advantage that the light shielding filter 96 as provided is not necessary. The transparent seal layer 98 and the adhesive layer 100 on the back surface that are formed so as to cover the correction marker 90B including the phosphor layer 94b are the same as those in the previous embodiment.

  FIG. 14 shows still another embodiment of the correction marker that prevents the formation of sagging at the edge portion. The correction marker 90C according to the present embodiment uses a frame-shaped light-shielding filter 96 made of a light-shielding member as in the embodiment shown in FIG. 11 (see FIG. 14A). 11 is different from the embodiment shown in FIG. 11 in that 96 is provided below the phosphor layer 94.

Since the correction marker 90C according to the present embodiment is configured as described above, reflection from the lower layer side when the phosphor layer 94 emits light is described above as indicated by a circle B in FIG. By suppressing with the light shielding filter 96, the emission light from the phosphor layer 94 is made to have a size corresponding to the size of the opening of the light shielding filter 96, and the region of the emitted light can be accurately detected. It is.
Here, the method for forming the light shielding filter 96 on the support 92 and the method for forming the phosphor layer 94 on the light shielding filter 96 are not particularly limited.

  The correction marker according to the present embodiment uses a stimulable phosphor having a light emission characteristic different from that of the first stimulable phosphor for image formation, and further, the first stimulable phosphor is used as erasing light. This is very unique in that a light source having an operating wavelength is used as the first excitation light. If such materials are found in addition to those exemplified in the future, those materials can be suitably used for the radiation image conversion panel according to the present invention and the radiation image acquisition system using the same. Nor.

  Further, the number of correction markers provided on the radiation image conversion panel may be any number from 1 to an arbitrary number, and a plurality of correction markers are provided so as to match the number of scanners so that the radiation image conversion panel is divided and read in parallel. It is also possible.

  It should be noted that the above-described embodiments and the like are merely examples of the present invention, and it is needless to say that appropriate changes and improvements may be made without departing from the spirit of the present invention.

For example, the phosphor constituting the correction marker is not limited to the photostimulable phosphor shown in the above-described embodiment, and other ordinary phosphors having no photostimulability can also be used according to the above-described embodiment. It is possible to obtain a part of the effect.
In addition, the correction marker according to the present invention can be suitably used even in the technique disclosed in Patent Document 3 according to the above-mentioned prior application of the present applicant.

It is a perspective view showing a schematic structure of a radiation image conversion panel concerning one embodiment of the present invention. They are the front view (a) and side view (b) which show schematic structure of the radiographic image reading apparatus which reads a radiographic image from a radiographic image conversion panel. It is sectional drawing which shows the internal structure of the reading part by which the light source and the line sensor were integrally arrange | positioned. It is a side view which shows a mode that the radiographic image conversion panel was located in the radiographic image recording position. It is a side view which shows a mode that the radiographic image conversion panel was located in the radiographic image reading position. It is a flowchart (the 1) which shows the image reading procedure in the radiographic image reading apparatus which concerns on one Embodiment. It is a flowchart (the 2) which shows the image reading procedure in the radiographic image reading apparatus which concerns on one Embodiment. It is a flowchart (the 3) which shows the image reading procedure in the radiographic image reading apparatus which concerns on one Embodiment. It is a figure which shows together the image of a radiographic image conversion panel, and the image of a correction marker, (a) is a figure which shows the radiographic image for a correction | amendment image | photographed with the uniform X-ray, (b) is image | photographed with the X-ray which passed the to-be-photographed object. It is a figure which shows the to-be-photographed object radiographic image. It is explanatory drawing of the method of determining the position of a correction marker from the image of a correction marker, (a) is a top view which shows the scan reading condition of a correction marker, (b), (c) is a graph which shows an example of reading data. is there. The correction marker for the radiographic image conversion panel which concerns on one Embodiment of this invention is shown, (a) is a top view, (b) is the sectional view on the AA line of (a). It is sectional drawing which shows the correction marker for the radiographic image conversion panel which concerns on other embodiment. It is sectional drawing which shows the correction marker for the radiographic image conversion panel which concerns on other embodiment. It is a figure which shows the correction marker for the radiographic image conversion panel which concerns on other embodiment, (a) is sectional drawing, (b) is a graph which shows light-emission quantity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radiation image conversion panel 1A, 1B Image area | region 2A, 2B, ... Correction marker 3A, 3B, ... Structural defect 10 Light source 30 Line sensor 32 Excitation light cut filter 33 CCD element 39 Erasing fluorescent lamp 50 Reading part 60 Image data processing unit 63 Image memory for correction 64 Subject image memory 65 Correction calculation unit 70 Panel base moving unit 75 Linear slide system 90, 90A, 90B, 90C Correction marker 92, 92a Support 92b Recessed portion 94, 94b, 94c Phosphor Layer 94a Sagging 96 Shading filter 98 Transparent seal layer 100 Adhesive layer

Claims (11)

A correction marker for position detection composed of a phosphor provided in a part of a radiation image conversion panel including a recording layer made of a stimulable phosphor (first accumulative phosphor),
A correction marker having an optically steep edge portion. The optically steep edge portion is
The correction marker according to claim 1, wherein the phosphor constituting the correction marker is formed by covering with a light shielding material having an opening. The optically steep edge portion is
2. The correction marker according to claim 1, wherein the correction marker is formed by cutting out the phosphor constituting the correction marker from one formed in a sheet shape and pasting the phosphor on a part of the radiation image conversion panel. The optically steep edge portion is
The correction marker according to claim 1, wherein the correction marker is formed by forming the phosphor constituting the correction marker in a recess formed in a part of the radiation image conversion panel. The optically steep edge portion is
The correction marker according to claim 1, wherein the correction marker is formed by disposing the phosphor constituting the correction marker on a light shielding material having an opening. The correction marker according to any one of claims 1 to 5,
Furthermore, a correction marker whose surface is covered with an optically transparent sealing material.   A radiation image conversion panel comprising the correction marker according to claim 1.   The radiation image conversion panel according to claim 7, wherein the correction marker is provided outside an image recording area (image area) of the radiation image conversion panel. As a phosphor constituting the correction marker,
A storage phosphor (second storage phosphor) that emits light having a wavelength shorter than the wavelength of secondary excitation light for the storage phosphor (first storage phosphor) constituting the recording layer is used. Item 9. The radiation image conversion panel according to Item 7 or 8. As a stimulable phosphor constituting the correction marker,
Using light that can erase the energy accumulated in the (first stimulable phosphor) as primary excitation light,
The radiation image conversion panel according to claim 7, wherein light that can secondarily excite the first stimulable phosphor is used as secondary excitation light. Using the radiation image conversion panel according to claim 9 or 10,
The stimulated emission light generated from the stimulable phosphor (first stimulable phosphor) constituting the recording layer on the radiation image conversion panel upon receiving the primary excitation light, and the first light on the correction marker Of the photostimulated luminescent light generated from the two storage phosphors through the imaging optical system and recorded as a latent image on the radiation image conversion panel, and an image of the correction marker recorded on the correction marker. Detecting means for acquiring an image signal representing a position;
After correcting the position of the radiographic image represented by the image signal based on the position of the image of the correction marker represented by the image signal, the position-corrected image signal is used to influence the emission unevenness of the stimulated emission light. A radiation image acquisition system comprising: a light emission unevenness correcting unit that acquires an image signal representing a removed radiation image.

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