JP2007193171A - Image reader and image reading method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an excellent diagnostic image free from image irregularity even when an image reader is shocked. <P>SOLUTION: In the image reading method, exciting light radiated from a light source is moved by a moving means when reading an image by photoelectrically converting stimulable luminescence generated by the exciting light radiated from the light source to a stimulable phosphor sheet or a plate member to which a stimulable phosphor sheet is attached. When detecting that an image reader main body is shocked (S03), the radiation of the exciting light is stopped and image reading is interrupted (S04). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image reading apparatus for performing image reading by photoelectrically converting stimulated emission light generated by excitation light emitted from a light source onto a stimulable phosphor sheet or a plate-like member attached with a stimulable phosphor sheet, and The present invention relates to an image reading method.

  Radiation images such as X-ray images are often used for disease diagnosis and the like. Traditionally, in order to obtain such radiation images, X-rays that have passed through a subject are applied to a phosphor layer (phosphor screen). So-called radiographs were used in which visible light was generated and irradiated to develop a film or the like using a silver salt in the same manner as when taking a normal photograph. However, in recent years, there has been devised a method for directly extracting an image from a phosphor layer without using a film coated with silver salt.

  As an example of this technique, radiation that has passed through a subject such as a patient is absorbed by the phosphor, and then the phosphor is excited by light or thermal energy, so that the phosphor accumulates due to the above absorption. Some radiate energy as fluorescence, and detect and image this fluorescence.

  For example, a stimulable phosphor plate having a stimulable phosphor layer formed on a support is used, and each part of the subject is irradiated with radiation transmitted through the subject to the stimulable phosphor layer of the stimulable phosphor plate. A latent image is formed by accumulating radiation energy corresponding to the radiation transmittance of the light, and then, by scanning the stimulable phosphor layer with stimulating excitation light, the accumulated radiation energy of each part is emitted. This is converted into light, and the intensity of the light is converted into an image signal through a photoelectric conversion means such as a photomultiplier to obtain a radiation image as digital image data.

  Based on such digital image data, an image is formed on a silver salt film, or an image is output to a CRT or the like for visualization. The digital image data is stored in an image storage device such as a semiconductor storage device, a magnetic storage device, or an optical disk storage device, and can then be taken out from these image storage devices as necessary and visualized via a silver salt film, a CRT, or the like. .

By the way, when the photostimulable fluorescent plate is scanned with the photostimulable excitation light, the photostimulable excitation light source must be precisely moved relative to the photostimulable fluorescence plate at a constant speed. For this reason, the following Patent Document 1 discloses a good transport method without image unevenness.
JP 2003-344964 A

  As described above, when the photostimulable phosphor is scanned with photostimulated excitation light, it is necessary to perform high-performance conveyance without image unevenness. However, the above-described conventional technique has high-performance without image unevenness in a steady state. Although speed conveyance is performed, when an impact is applied to the image reading apparatus, uniform speed conveyance is hindered, thereby causing unevenness in the speed of the conveyance unit and scanning the photostimulable fluorescent plate with photostimulated excitation light. In some cases, the image becomes uneven, and the diagnostic image may be hindered.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide an image reading apparatus and an image reading method capable of obtaining a good diagnostic image without image unevenness even when an impact is applied to the apparatus. To do.

  In order to achieve the above object, an image reading apparatus according to the present invention emits stimulating light emitted by excitation light irradiated from a light source onto a stimulable phosphor sheet or a plate-like member attached with a stimulable phosphor sheet. An image reading apparatus for moving excitation light irradiated from the light source by a moving means when performing image reading by photoelectric conversion, comprising an impact detection means for detecting that an impact has been applied to the image reading apparatus, When an impact is detected by the impact detection means, irradiation of the excitation light is stopped and the image reading is interrupted.

  According to this image reading apparatus, when the impact detecting means detects that an impact has been applied to the image reading apparatus, irradiation of excitation light to the stimulable phosphor sheet / plate member is stopped and image reading is interrupted. Thus, since the image reading is not performed while the constant speed conveyance by the moving means such as the linear motor is inhibited, the occurrence of image unevenness can be suppressed. As a result, when the photostimulable phosphor sheet / plate member is scanned with excitation light, a good image without image unevenness can be obtained.

  The image reading apparatus further includes position detecting means for detecting a moving position of the excitation light irradiated from the light source, the position detecting means detects the position where the image reading is interrupted, and the interruption is performed after the impact is settled. The image reading is performed again from the position. As described above, the position detection unit detects the position where the image reading is interrupted, and after the impact is stopped, the image reading is executed again from the interrupted position, whereby a good diagnostic image without image unevenness can be obtained.

  Further, the impact applied to the moving means can be efficiently detected by arranging the impact detecting means at least in the vicinity of the moving means. The impact detection means can be constituted by an acceleration sensor.

  The image reading method according to the present invention performs image reading by photoelectrically converting stimulated emission light generated by excitation light irradiated from a light source onto a stimulable phosphor sheet or a plate-like member attached with a stimulable phosphor sheet. In the image reading method of moving the excitation light emitted from the light source by the moving means when detecting that an impact has been applied to the apparatus body for performing the image reading, the irradiation of the excitation light is stopped, The image reading is interrupted.

  According to this image reading method, when it is detected that an impact has been applied to the main body of the image reading apparatus, irradiation of excitation light to the stimulable phosphor sheet / plate-like member is stopped and image reading is interrupted. Since the image reading is not performed while the constant speed conveyance by the moving means such as the linear motor is hindered, the occurrence of image unevenness can be suppressed. As a result, when the photostimulable phosphor sheet / plate member is scanned with excitation light, a good image without image unevenness can be obtained.

  In the image reading method, the position where the image reading is interrupted is detected, and after the impact is stopped, the image reading is executed again from the interrupted position. In this way, by detecting the position where the image reading is interrupted and executing the image reading again from the interrupted position after the impact is settled, a good diagnostic image without image unevenness can be obtained. It should be noted that the impact applied to the apparatus main body can be detected by the acceleration sensor.

  According to the image reading apparatus and the image reading method of the present invention, a good diagnostic image without image unevenness can be obtained even when an impact is applied to the apparatus.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a main part perspective view schematically showing main parts of the radiation image reading apparatus according to the present embodiment. FIG. 2 is a right side view of an essential part of the radiographic image reading apparatus of FIG. FIG. 3 is a left side view of the main part of the radiation image reading apparatus of FIG. FIG. 4 is a top view of the main part of the radiation image reading apparatus of FIG. FIG. 5 is a front view of an essential part of the radiographic image reading apparatus of FIG. FIG. 6 is a control block diagram showing the main part of the control system of the radiation image reading apparatus of FIG.

  In the radiation image reading apparatus 10 according to the present embodiment shown in FIGS. 1 to 5, the radiation transmitted through the subject is absorbed by the stimulable phosphor sheet 204, and a part of the energy is emitted into the stimulable phosphor. It is stored as image information, and radiographic image information stored in the photostimulable phosphor is read, and is particularly suitable for use in the medical field.

  The radiographic image reading apparatus 10 includes an optical unit 100 equipped with a stimulable excitation light source 110 (FIG. 6) for irradiating a stimulable phosphor sheet 204 with a stimulable excitation laser beam, and a stimulable fluorescence from the stimulated excitation light source. A stimulating light-emitting condenser tube 105 that collects the photostimulated luminescent light generated by laser light irradiation on the body sheet 204, and a photoelectric converter 102 that converts the light from the photostimulated luminescent condenser tube 105 into an electrical signal. . The electrical signal from the photoelectric converter 102 passes through an analog / digital conversion circuit (not shown) and is visualized or exposed to a silver salt film (not shown) to be visualized.

  1 to 5, illustration of a light shielding member that shields the entire apparatus from external light and a main body cover that covers the main body are omitted. Further, the photostimulable phosphor sheet 204 is not rigid alone, is difficult to handle in the apparatus, and is rarely handled alone. Therefore, the photostimulable phosphor sheet 204 is often a support member such as a metal plate and a resin plate, or photostimulability. It is often handled in a state where it is held and adhered to the inner surface of the back plate (on the opposite side of the imaging surface side of the cassette) which is configured to be removable such as a cassette for storing the fluorescent plate, For this reason, in this Embodiment, it is set as the structure which uses the photostimulable fluorescent plate P supported by the photostimulable fluorescent substance sheet 204 with the support member, and was formed in the plate-shaped member.

  The radiographic image reading apparatus 10 includes a fixing base 205 for fixing the photostimulable fluorescent plate P taken and transported inside the apparatus by a plate transporting means (not shown) with a rubber magnet, and the fixing base 205 as a frame. A base 201 fixed by (not shown), a transport base 202 that supports and fixes the optical unit 100, and a transport base 202 that supports the optical unit 100 along the linear guide rail 203 in the horizontal direction (sub-scanning direction). And a linear motor 300 provided on the base 201 so as to be moved.

  The linear motor 300 includes a magnet unit 301 that is a drive source that moves the transport table 202 in the sub-scanning direction (x-axis direction), and a linear motor movable unit 302 connected to the transport table 202. The magnet portion 301 has a shaft-like shape and is arranged substantially parallel to the linear motion guide rail 203 in the sub-scanning direction (x-axis direction). The carriage 202 is moved by the linear motor 300 while being guided in the sub-scanning direction by the linear motion guide rail 203, and the optical unit 100 is transported in the sub-scanning direction.

  In addition, a rotary encoder unit 303 is fixed to the transport table 202 in order to control the position and speed of the linear motor 300. The rotary encoder unit 303 includes a rotary encoder 401, a support member 404 that supports the rotary encoder 401 and is fixed to the transport table 202, and a pulley 402 that is fixed to the rotary shaft of the rotary encoder 401.

  A wire 304 is arranged substantially parallel to the linear motion guide rail 203 and the sub-scanning direction, and both ends of the wire 304 are fixed to fixing members 305A and 305B. When the optical unit 100 is moved in the sub-scanning direction by the linear motor 300, the rotating shafts of the pulley 402 and the rotary encoder 401 are rotated by the wire 304. As a result, the rotational speed of the rotary encoder 401 of the rotary encoder unit 303 is detected and output to the linear motor control unit 701 in FIG.

  The optical unit 100 is fixed to the carrier table 202 and is sub-scanned in the sub-scanning direction (x-axis direction) by the linear motor 300. The optical unit 100 forms an image of the laser beam emitted from the stimulating excitation light source with an imaging lens, and The main scanning is performed in the main scanning direction (y-axis direction) by a deflecting mirror such as a mirror.

  The linear motor 300 moves the optical unit 100 to a position facing the laser light irradiation surface of the photostimulable fluorescent plate P, and the optical unit 100 moves in the sub-scanning direction. Exhaust excitation laser light L1 is irradiated to the photostimulable phosphor sheet 204. At this time, since a light emission phenomenon occurs in accordance with the latent image formed by radiation irradiation from the photostimulable phosphor layer on the surface of the photostimulable phosphor sheet 204, the photostimulated light L2 is stimulated by the light guide plate 101. The light is emitted to the light emission condenser tube 105, condensed by the stimulable light emission condenser tube 105, and converted into an electric signal by the photoelectric converter 102.

  A support base 206 that supports the linear guide rail 203 described above is fixed to the base 201, and the support base 206 has a linear scale 501 disposed so as to extend in the sub-scanning direction (x-axis direction); An acceleration sensor 601 for detecting that an external impact has been applied to the radiation image reading apparatus 10 is provided.

  The linear encoder 500 includes the above-described linear scale 501 and a linear encoder head 502 provided at the bottom of the optical unit 100, and detects the movement position of the optical unit 100 in the sub-scanning direction.

  The acceleration sensor 601 is configured to be able to detect an impact force in three axis directions. For example, the acceleration sensor 601 includes a piezoelectric type using a piezoelectric element that generates an electric charge when subjected to an inertial force, but is of another type. May be.

  The acceleration sensor 601 attached to the support base 206 operates so as to always detect an impact applied from the outside to the radiation image reading apparatus 10 and is disposed in the vicinity of the linear motor 300 so that the impact from the outside is applied to the linear motor 300. It is possible to efficiently detect the influence on the image.

  As shown in FIG. 6, the radiation image reading apparatus 10 includes a control unit 700 including a CPU (Central Processing Unit) that controls the entire apparatus, and the control unit 700 detects the rotation speed detected by the rotary encoder 401. By controlling the linear motor 300 via the linear motor control unit 701 based on the above, the sub-scanning movement of the optical unit 100 is controlled.

  In addition, the control unit 700 receives a signal from the acceleration sensor 601, and when the impact force detected by the acceleration sensor 601 during image reading is equal to or greater than a predetermined value, the photostimulable phosphor sheet from the stimulating excitation light source 110 is used. Control is performed so that the image reading is interrupted by stopping the light irradiation to 204.

  When the image reading is interrupted, the control unit 700 stores the interruption position in the sub-scanning direction of the optical unit 100 measured by the linear encoder 500 in the memory 702, and when the acceleration sensor 601 detects that the impact has stopped, the optical unit 100 100 is once returned to the movement origin position, and then the reading operation is started without irradiating the excitation laser beam L1. When the optical unit 100 moves to the sub scanning position and reaches the interruption position of the image reading stored in the memory 702, Control is performed so that image reading is resumed by irradiating the excitation laser beam L1 again.

  Next, operations S01 to S08 of the radiation image reading apparatus 10 of FIGS. 1 to 6 will be described with reference to the flowchart of FIG.

  First, when the photostimulable fluorescent plate P taken into the radiation image reading apparatus 10 is fixed to the fixed base 205 (S01), the optical unit 100 moves from the moving origin position to the main scanning direction (y-axis direction) and the sub-scanning direction. Scanning is started in the scanning direction (x-axis direction) and reading of radiation image information is started (S02).

  By the above scanning, the photostimulable phosphor sheet 204 of the photostimulable phosphor plate P is irradiated with the photostimulated excitation laser light L1 from the photostimulated excitation light source 110 (FIG. 6) of the optical unit 100, and the photostimulated excitation laser light. The stimulated emission light L2 generated by the irradiation of L1 is guided to the photostimulated emission collector tube 105 by the light guide plate 101, condensed by the photostimulated emission collector tube 105, and converted into an electric signal by the photoelectric converter 102. Then, the radiation image information accumulated in the photostimulable phosphor sheet 204 of the photostimulable phosphor plate P is read.

  During the reading of the radiation image information described above, the acceleration sensor 601 operates to detect an impact applied to the radiation image reading apparatus 10 from the outside, and when an impact force of a predetermined value or more is detected (S03), Light emission from the excitation light source 110 to the photostimulable phosphor sheet 204 is stopped, and radiation image reading is interrupted (S04).

  Then, the interruption position detected by the linear encoder 500 is stored in the memory 702 of FIG. 6 (S05), and when it is detected that the impact force detected by the acceleration sensor 601 is equal to or less than a predetermined value (S06). When the optical unit 100 returns to the moving origin position, reading operation is started without irradiating the excitation laser beam L1, and when the optical unit 100 moves to the sub scanning position and reaches the interruption position, the excitation laser beam L1 is irradiated again. Then, image reading is resumed (S07).

  Further, the acceleration sensor 601 always operates so as to detect an impact applied to the radiation image reading apparatus 10 from the outside until the radiation image reading is completed (S08).

  According to the operation of the radiographic image reading apparatus 10 described above, even if an external impact is applied to the radiographic image reading apparatus 10 for some reason during the radiographic image reading, the image reading is interrupted until the impact is reduced. Thus, no unevenness of image occurs and a good diagnostic image can be obtained.

  Note that the image reading is resumed by irradiating the excitation excitation laser beam L1 from the optical unit 100 again at the interruption position where the radiation image reading is interrupted, but the joint between the image read before the interruption and the image read after the reading is resumed. Can be made inconspicuous visually by image correction processing.

  In addition, the predetermined value of the impact force detected by the acceleration sensor 601 can be appropriately set in the control unit 700 according to the degree of image unevenness that occurs due to the impact on the linear motor 300 or the like due to the impact. .

  As described above, the best mode for carrying out the present invention has been described. However, the present invention is not limited to these, and various modifications are possible within the scope of the technical idea of the present invention. For example, in the present embodiment, the speed control of the linear motor 300 is configured to be performed using a rotary encoder, a pulley, and a wire. However, the present invention is not limited to this and, for example, is performed using a linear encoder. You may comprise.

  Further, in this embodiment, the sub-scanning movement of the stimulated excitation laser light by the relative movement between the optical unit 100 and the photostimulable fluorescent plate P at the time of image reading is performed by moving the optical unit 100. However, this invention is not limited to this, You may comprise so that the photostimulable fluorescent plate P may be moved.

It is a principal part perspective view which shows schematically the principal part of the radiographic image reading apparatus by this Embodiment. It is a principal part right view of the radiographic image reading apparatus of FIG. It is a principal part left view of the radiographic image reading apparatus of FIG. It is a principal part top view of the radiographic image reading apparatus of FIG. It is a principal part front view of the radiographic image reading apparatus of FIG. It is a control block diagram which shows the principal part of the control system of the radiographic image reading apparatus of FIG. It is a flowchart for demonstrating operation | movement S01-S08 of the radiographic image reading apparatus 10 of FIG. 1 thru | or FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Radiation image reader 100 Optical unit 102 Photoelectric converter 105 Stimulated light emission condensing tube 110 Stimulated excitation light source 201 Base 202 Carrying stand 204 Stimulable phosphor sheet 300 Linear motor (moving means)
301 Magnet unit 302 Linear motor movable unit 303 Rotary encoder unit 304 Wire 401 Rotary encoder 402 Pulley 404 Support member 500 Linear encoder 601 Acceleration sensor (impact detection means)
700 Control Unit 701 Linear Motor Control Unit 702 Memory L1 Bright Excitation Laser Light (Excitation Light)
L2 photostimulated luminescence light P photostimulable fluorescent plate (plate member)

Claims (6)

When the photostimulable phosphor sheet or the plate-like member attached with the photostimulable phosphor sheet is subjected to photoelectric conversion of the photostimulated luminescent light generated by the excitation light irradiated from the light source to read the image, the moving means removes the light source from the light source. An image reading apparatus that moves excitation light to be irradiated,
Comprising an impact detection means for detecting that an impact has been applied to the image reading device;
When an impact is detected by the impact detection means, the image reading apparatus stops irradiation of the excitation light and interrupts the image reading. Further comprising position detecting means for detecting the moving position of the excitation light irradiated from the light source;
The image reading apparatus according to claim 1, wherein the position where the image reading is interrupted is detected by the position detecting unit, and the image reading is executed again from the interrupted position after the impact is stopped.   The image reading apparatus according to claim 1, wherein the impact detection unit is disposed at least in the vicinity of the moving unit.   The image reading apparatus according to claim 1, wherein the impact detection unit includes an acceleration sensor. When the photostimulable phosphor sheet or the plate-like member attached with the photostimulable phosphor sheet is subjected to photoelectric conversion of the photostimulated luminescent light generated by the excitation light irradiated from the light source to read the image, the moving means removes the light source from the light source. An image reading method for moving excitation light to be irradiated,
An image reading method comprising: stopping the irradiation of the excitation light and interrupting the image reading when it is detected that an impact is applied to an apparatus main body that performs the image reading.   The image reading method according to claim 5, wherein a position where the image reading is interrupted is detected, and the image reading is executed again from the interrupted position after the impact is stopped.

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