JP2005275006A - Image information acquisition method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To use a user-friendly photodetector to acquire image information held in a stimulable phosphor sheet in a dynamic range wider than that of the photodetector. <P>SOLUTION: When the intensity of stimulated luminescence emitted by main scanning and subscanning of exciting light on a stimulable phosphor sheet 20, exciting light Le2 having a low intensity is radiated to odd-numbered main scanning lines by arranging an attenuator 14 on an optical path, to detect the intensity of emitted stimulated luminescence Kh2 by a PMT 31, and exciting light Le having a high intensity is radiated to even-numbered main scanning lines by retreating the attenuator, to detect the intensity of emitted stimulated luminescence Kh by the PMT 31. In an image processing part 42, the intensity of stimulated luminescence Kh is used as a pixel value with respect to a pixel where the intensity of stimulated luminescence Kh is equal to or lower than a light intensity threshold S1, and a value resulting from multiplying the intensity of stimulated luminescence Kh2 with a multiplication factor K is used as a pixel value with respect to a pixel where the intensity of stimulated luminescence Kh is larger than the threshold S1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image information acquisition method and apparatus, and more particularly, to detect and store stimulated emission light emitted from a stimulable phosphor sheet when the stimulable phosphor sheet on which radiation image information is recorded is irradiated with excitation light. The present invention relates to an image information acquisition method and apparatus for acquiring radioactive image information recorded on a fluorescent phosphor sheet.

  When irradiated with radiation, a part of this radiation energy is accumulated, and when irradiated with excitation light such as visible light or laser light thereafter, a stimulable phosphor that emits stimulated emission light corresponding to the accumulated radiation energy (brightness) An apparatus using an exhaustive phosphor) is known. For example, a radiation image of a test object is once accumulated and recorded on a sheet-like stimulable phosphor sheet formed by laminating the stimulable phosphor, and then the stimulable phosphor sheet is irradiated in two dimensions with excitation light. An image information acquisition device that sequentially generates stimulated emission light from each position of the sheet, photoelectrically detects these stimulated emission light, and acquires radiation image information recorded on the stimulable phosphor sheet. It is used for practical use.

  Further, the present applicant replaces the stimulable phosphor sheet with a support on which a plurality of spot areas where substances labeled with the fluorescent label are distributed is placed on the scanning table. An image information acquisition device that can acquire both image information recorded on the stimulable phosphor sheet and image information of fluorescence emitted from the spot area of the support is also proposed. (For example, refer to Patent Document 1).

  Further, the excitation light is sequentially irradiated to the spot area of the support in which a plurality of spot areas in which a substance labeled with a fluorescent label that emits fluorescence upon irradiation of the excitation light is distributed is set. There is also known a fluorescence image information acquisition apparatus that acquires an image of fluorescence emitted from a fluorescent label (see, for example, Patent Document 2).

In the fluorescence image information acquisition device described in Patent Document 2, each spot area of the support is irradiated with excitation light having a low light intensity, the intensity of the fluorescence emitted by the irradiation is detected, and then the same spot area is detected. Excitation light with high light intensity is irradiated, the intensity of the fluorescence emitted by the irradiation is detected, and the fluorescence intensity of the fluorescence emitted from the spot region is calculated based on the detected light intensity of the two types of fluorescence . For this reason, the fluorescence image emitted from the spot region can be acquired with a dynamic range wider than the dynamic range of the photodetector using a photodetector with a narrow dynamic range that is easy to use.
JP 2001-100341 A JP 2003-232733 A

  However, when acquiring radiographic image information recorded by two-dimensionally scanning the stimulable phosphor sheet with excitation light, as described in Patent Document 2, irradiation with excitation light with low light intensity is performed, Even if the stimulated emission light emitted by the irradiation is detected, and then the excitation light having a high light intensity is irradiated and the stimulated emission light emitted by the irradiation is detected, the stimulated emission light has already been emitted. Therefore, there is a problem in that photostimulated luminescence light with sufficient light intensity cannot be obtained, and image information cannot be acquired with a wide dynamic range.

  In view of the above circumstances, the present invention provides an image information acquisition method capable of acquiring image information recorded on a stimulable phosphor sheet in a dynamic range wider than the dynamic range of the photodetector, using an easy-to-use photodetector. And an object of the present invention.

The image information acquisition method of the present invention irradiates a predetermined region of a stimulable phosphor sheet on which a radiographic image is recorded with excitation light, detects the intensity of light emitted from the predetermined region by the irradiation, and detects the detected light. An image information acquisition method for acquiring image information held in the predetermined area based on the light intensity,
A part of the predetermined region is irradiated with first excitation light to give first light energy, and the intensity of the first light emitted from the predetermined region is detected by the application of the first light energy. Then, the second excitation light is irradiated to a region including the remaining part of the predetermined region to give a second light energy having a light energy amount different from the first light energy, The intensity of the second light emitted from the predetermined area is detected by applying light energy, and the predetermined area is held based on the detected intensity of the first light and the intensity of the second light. Image information is acquired.

The image information acquisition apparatus of the present invention irradiates a predetermined region of a stimulable phosphor sheet on which a radiographic image is recorded with excitation light, detects the intensity of light emitted from the predetermined region by the irradiation, and detects the detected light. An image information acquisition device that acquires image information held in the predetermined area based on the light intensity,
The first excitation light is irradiated to a part of the predetermined region to give the first light energy, and then the second excitation light is irradiated to the region including the remaining part of the predetermined region. Excitation light irradiation means for applying a second light energy having a light energy amount different from the light energy of 1, the intensity of the first light emitted from the predetermined region by the application of the first light energy, A light detecting means for detecting the intensity of the second light emitted from the predetermined region by the application of the second light energy; the intensity of the first light detected by the light detecting means; and the second light. Image information generating means for acquiring image information held in the predetermined area based on the intensity of the image.

  Further, “acquiring information held in the predetermined area based on the intensity of the first light and the intensity of the second light detected by the light detection means” means that one pixel area The portion can emit stimulated emission light by excitation, but irradiates the first excitation light with a small amount of light energy, detects the intensity of the first stimulated emission light, and detects one pixel. By irradiating the region including the remaining part of the region with the second excitation light having a large amount of light energy and detecting the intensity of the second stimulated light emitted, the second stimulated light is emitted. In a pixel whose light intensity is equal to or lower than a preset light intensity threshold value, the detected value of the light intensity of the second stimulated emission light is used as the pixel value, and the light intensity of the second stimulated emission light is the light intensity threshold value. If larger, the detection value of the light intensity of the first stimulated emission light is multiplied by a preset value. Can be are used as the pixel value a value obtained by multiplying by.

  Here, “light energy” means the energy of excitation light applied to the predetermined region, and is light intensity of the excitation light × irradiation area × irradiation time. The energy amounts of the first light energy and the second light energy may be different by a factor of two or more.

  The excitation light irradiating means is configured to perform main and sub scanning of the stimulable phosphor sheet with the beam-shaped first excitation light and the beam-shaped second excitation light, and with the first excitation light. The odd-numbered main scanning lines may be scanned, and the even-numbered main scanning lines may be scanned with the second excitation light.

  The first excitation light and the second excitation light may be spot-shaped light or line-shaped light extending in the main scanning direction. In the case of spot light, main / sub scanning may be performed by moving the spot light, or main / sub scanning may be performed by moving the stimulable phosphor sheet. Alternatively, one of the main scanning and the sub scanning may be performed by moving the spot-like light, and the other scanning may be performed by moving the stimulable phosphor sheet. In the case of line-shaped light, two-dimensional scanning can be performed by alternately irradiating the first excitation light or the second excitation light for each main scanning line. In the scanning in the sub-scanning direction, line-shaped light may be moved, or the stimulable phosphor sheet may be moved. When line-shaped light is used as excitation light, it is preferable to use a line-shaped photodetector extending in the main scanning direction, such as a line CCD, as the photodetector. Further, the odd-numbered main scanning lines and the even-numbered main scanning lines do not necessarily have to be scanned alternately. For example, first, all the odd-numbered main scanning lines are scanned with the first excitation light, and thereafter All the even-numbered main scanning lines may be scanned with the second excitation light.

  Of the first excitation light and the second excitation light, the beam diameter of the excitation light that imparts large light energy may be larger than the beam diameter of the other excitation light.

  The image information acquisition method and apparatus of the present invention apply a first light energy by irradiating a part of the predetermined area with a first excitation light, and from the predetermined area by applying the first light energy. The intensity of the emitted first light is detected, and then the second excitation light is irradiated to a region including the remaining part of the predetermined region, and the second light energy is different from the first light energy. Is applied, and the second light energy is applied to detect the intensity of the second light emitted from the predetermined region, and the detected intensity of the first light and the second light are detected. By acquiring the information held in the predetermined area based on the intensity, the information held in the predetermined area is acquired in a wider dynamic range than the dynamic range of the photodetector using a convenient photodetector. can do.

  The excitation light irradiating means performs main / sub-scanning of the stimulable phosphor sheet with the beam-like first excitation light and the beam-like second excitation light, and with the first excitation light. If the odd-numbered main scanning line is scanned and the even-numbered main scanning line is scanned by the second excitation light, only a slight change is made to the existing main / sub scanning type image information acquisition device. The image information acquisition apparatus of the present invention can be realized.

  Of the first excitation light and the second excitation light, when the beam diameter of the excitation light that gives large light energy is larger than the beam diameter of the other excitation light, it is recorded on the stimulable phosphor sheet. Even if the amount of radiation image information is small, the image information can be acquired with high accuracy.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of an image information acquisition apparatus to which an image information acquisition method according to an embodiment of the present invention is applied. The image information acquisition apparatus 800 includes an optical system 100 that irradiates the stimulable phosphor sheet 20 that accumulates radiation images with excitation light emitted from a laser light source, a recording medium transport unit 200 that transports the stimulable phosphor sheet 20, The main part is composed of a detection unit 300 that detects the stimulated emission light emitted by the stimulable phosphor sheet 20 irradiated with excitation light, and a signal processing unit 400 that processes a signal detected by the detection unit 300. ing.

  The optical system 100 includes a laser light source 11 that is a semiconductor laser that emits excitation light having a wavelength of 633 nm. The optical intensity of the excitation light Le is reduced to 1/10 in the optical path of the excitation light Le emitted from the laser light source 11. Attenuating plate 14 is disposed to damp. The attenuation plate 14 is retracted from the optical path under the control of the control unit 60 described later. The excitation light Le is incident on a rotating polygon mirror 17 driven by a polygon motor 16.

  The excitation light Le incident on the polygon mirror 17 is reflected and deflected by the polygon mirror 17, reflected by the reflecting mirror 19 through the fθ lens 18 at a substantially right angle, and then incident on the storage phosphor sheet 20. The excitation light Le deflected by the polygon mirror 17 scans the stimulable phosphor sheet 20 linearly in the X direction at a constant speed by the action of the fθ lens 18.

  A sample stage 22 having an opening in the center is movably disposed in the recording medium transport unit 200, and a stimulable phosphor in which a stimulable phosphor layer containing a stimulable phosphor is laminated on the lower surface 20a. The body sheet 20 is mounted on and integrated with a sheet sample holder 21 having an opening at the center and formed of aluminum or the like, and is placed on the sample stage 22. The sample stage 22 is transferred in the Y direction, that is, in the sub-scanning direction by a transfer mechanism (not shown) in synchronization with the main scanning in the X direction of the excitation light Le, whereby the lower surface 20a of the stimulable phosphor sheet 20 is transferred. Are scanned two-dimensionally by the excitation light Le.

  The detection unit 300 receives from one end stimulated emission light generated from the stimulable phosphor sheet 20 by irradiation with excitation light Le that linearly scans the lower surface 20a of the stimulable phosphor sheet 20 in the X direction. A light guide 30 that changes the traveling direction and is emitted from the other end, and a PMT (photomultiplier) 31 that detects the stimulated emission light emitted from the light guide 30 and converts it into an electrical signal are disposed. The light guide 30 is made by processing non-fluorescent glass or the like, and its incident end 30a has an elongated linear opening, its emission end 30b is formed in a cylindrical shape, and the incident end 30a. Stimulated luminescence light Kh incident on the inner surface of the light guide 30 is propagated through the inside of the light guide 30 while repeating the total reflection on the inner surface and changing the traveling direction, and is emitted from the emission end 30b toward the PMT 31. An excitation light cut filter 32 that does not transmit light having a wavelength band of 500 nm or longer is disposed between the PMT 31 and the emission end 30b of the light guide 30.

  The signal processing unit 400 includes an A / D converter 40 that performs A / D conversion on the signal acquired by the PMT 31 at a predetermined sampling period. The A / D converted image signal is stored in the stimulable phosphor sheet 20. After being accumulated in the line buffer 41 for every scan of the stimulated emission light generated from the image signal, the image signals sequentially obtained from the odd-numbered lines are sequentially sent from the even-numbered lines to the image buffer 43a of the image processing unit 42. The acquired image signal is output to the image buffer 43b. In the image processing unit 42, the light intensity threshold value S1 and the multiplication factor K stored in advance in the memory 44 and the images stored in the image buffer 43a and the image buffer 43b are stored. Based on the signal, a video signal for one image is generated and output to the display 50. Details of the light intensity threshold S1, the multiplication factor K, and the image processing in the image processing unit 42 will be described later.

  The control unit 60 controls the oscillation of the laser light source 11, the arrangement and withdrawal of the attenuation plate 14, the synchronization between the main scanning of the excitation light and the sub-scanning of the sample stage 22. The control unit 60 arranges the attenuation plate 14 on the optical path when performing the odd-line main scanning, and retracts the attenuation plate 14 from the optical path when performing the even-line main scanning. Hereinafter, the excitation light whose light intensity is attenuated to 1/10 by the attenuation plate 14 is referred to as excitation light Le2. Note that the light intensity of the excitation light may be changed by changing the drive current supplied to the laser light source 11. Alternatively, as the laser light source 11, two semiconductor lasers and a multiplexing optical system are provided. As the excitation light Le, light obtained by combining the light emitted from the two semiconductor lasers is used, and as the excitation light Le2, one semiconductor is used. You may use the light inject | emitted from the laser.

  Further, the above mechanism is incorporated in a casing 500 having an appearance as shown in FIG. 2, and the sheet sample holder 21 on which the stimulable phosphor sheet 20 is mounted is placed on the sample stage 22. The radiation image transferred in the Y direction and recorded on the stimulable phosphor sheet 20 is read.

  Next, the operation of the image information acquisition method and apparatus according to the embodiment of the present invention will be described. First, the principle of acquiring a radiation image in the present embodiment will be described. When the radiation image recorded on the stimulable phosphor sheet 20 is read, the stimulated emission light emitted from the stimulable phosphor sheet 20 by the irradiation of excitation light is detected. When the stimulable phosphor of the stimulable phosphor layer laminated on the lower surface 20a of the stimulable phosphor sheet 20 is stimulated with excitation light, the maximum intensity is a wavelength near 400 nm as shown in FIG. Of light emission. When the stimulable phosphor is excited by excitation light Le having a high light intensity, stimulated emission light Kh is emitted. On the other hand, although the stimulated emission light can be generated by excitation with the excitation light Le2 having a low light intensity, the stimulated emission light Kh2 generated as shown in FIG. 3B when the excitation light Le2 is irradiated. The strength of becomes weaker. In the present embodiment, by using this characteristic, a pixel having a high light intensity of the stimulated emission light is used as a pixel value in a pixel having a low light intensity of the stimulated emission light as a pixel value. Then, a value obtained by multiplying the detection value of the light intensity of the stimulated emission light Kh2 by a predetermined value is used as the pixel value.

  In order to perform such image processing, first, an accumulative phosphor sheet sample irradiated with radiation of different known radiation intensities in several stages, for example, 10 stages, is prepared prior to the actual image information acquisition operation. First, each sample is irradiated with excitation light Le2 having a low light intensity, and the light intensity of the stimulated emission light Kh2 emitted from the portion irradiated with the excitation light Le2 is detected. Next, each sample is irradiated with excitation light Le having a high light intensity, and the light intensity of the stimulated emission light Kh emitted from the portion irradiated with the excitation light Le is detected. Note that the beam diameters and light intensities of the excitation light Le2 and the excitation light Le are set to the same values as when image information is actually acquired. In addition, once the photostimulated luminescence is emitted, the recorded image information is erased. Therefore, the excitation light Le2 and the excitation light Le irradiate different portions on the sample.

  FIG. 4 is a schematic diagram showing the relationship between the radiation intensity and the light intensity of the stimulated emission light Kh2 and the stimulated emission light Kh obtained in this way. An example of a method for obtaining the light intensity threshold value S1 and the multiplication factor K will be described with reference to this schematic diagram. First, it can be seen from FIG. 4 that the maximum light intensity value detectable by the PMT 31 is about 6.25 (relative value: hereinafter referred to as a relative value). Further, when the light intensity of the stimulated emission light Kh is 5, that is, when the radiation intensity is 2.5 (relative value: hereinafter referred to as a relative value), the light intensity of the stimulated emission light Kh2 is 0.5. From this, it can be seen that the light intensity value corresponding to the light intensity of the stimulated emission light Kh can be calculated by multiplying the value of the stimulated emission light Kh2 by about ten times. Based on this detection result, 5 which is 80% of the detectable light intensity of the PMT 31 is input as the light intensity threshold S1 from the input device 61 to the memory 44 of the image processing unit 42, and 10 is input as the multiplication factor K. To do.

  When actually reading out the radiation image information, the stimulable phosphor sheet 20 on which the radiation image is recorded is mounted on the sheet sample holder 21, and the sheet sample holder 21 is further placed on the sample stage 22. The control unit 60 outputs control signals to the laser light source 11, the attenuator 14 and the polygon motor 16.

  First, when the excitation light is irradiated to the first main scanning line (X direction), the excitation light is emitted from the laser light source 11 in a state where the attenuator 14 is arranged on the optical path of the excitation light, and the polygon motor 16 is emitted. Thus, the excitation light Le2 is scanned in the main scanning direction (X direction).

  When scanning in the main scanning direction (X direction) on the stimulable phosphor sheet 20 is completed, the sample stage 22 is conveyed by one line in the Y direction. Before the scanning of the second main scanning line (X direction), the attenuator 14 is retracted from the optical path of the excitation light. In this state, excitation light is emitted from the laser light source 11, excitation light is emitted from the first laser light source 11, and the excitation light Le is scanned by the polygon motor 16 in the main scanning direction (X direction).

  In this manner, the lower surface of the stimulable phosphor sheet 20 is alternately irradiated with the excitation light Le2 or the excitation light Le, and the stimulable phosphor sheet 20 is scanned two-dimensionally. By the two-dimensional scanning of the excitation light, the stimulable phosphor sheet 20 emits the stimulated emission light Kh 2 or the stimulated emission light Kh, and this stimulated emission light passes through the light guide 30 and the excitation light cut filter 32 to the PMT 31. Incident light, photoelectrically converted by the PMT 31, and output to the signal processing unit 400 as an image signal. Since the filter 32 is disposed in front of the PMT, the excitation light Le2 or the reflected light of the excitation light Le does not enter the PMT 31. Note that a pair of upper and lower detection parts acquired from the odd numbered line and the even numbered line below that function as a predetermined region of the present invention, that is, one pixel of the stimulable phosphor sheet.

  The image signal detected by the PMT 31 is converted into a digital signal by the A / D converter 40 and stored in the line buffer 41 for each main scanning of the stimulated light emission generated from the stimulable phosphor sheet 20. Sequentially, image signals acquired from odd-numbered main scanning lines are output to the image buffer 43a of the image processing unit 42, and image signals acquired from even-numbered main scanning lines are output to the image buffer 43b.

  In the image processing unit 42, first, for each pixel stored in the image buffer 43 b, the stored light intensity value is compared with the light intensity threshold value S 1 stored in the memory 44. If the stored light intensity value is less than or equal to the light intensity threshold S1, the light intensity value stored in the image buffer 43b is left as it is. If the stored light intensity value is greater than the light intensity threshold value S1, it is unlikely that the value reflects the actual radiation dose, so one scan line stored in the image buffer 43a Is multiplied by the multiplication factor K, and the value is stored in the image buffer 43b. All pixels are subjected to the same processing, and then a video signal for one image is generated based on the image signal stored in the image buffer 43 b and output to the display 50. Since the number of lines in the main scanning direction of the pixels stored in the image buffer 43b is half of the normal number, when generating a video signal, the video signal is generated after correcting that point. If the sampling timing of the signal output from the PMT 31 is adjusted in advance, the resolution in the main and sub scanning directions can be made equal. For example, if the sampling interval in the main scanning direction is 100 μm and the sub scanning line interval is 50 μm, the size of one pixel is 100 μm × 100 μm, and the resolution in the main sub scanning direction is equal. In the present embodiment, since the beam diameters of the excitation light Le and the excitation light Le2 are the same and the scanning speed is also the same, the difference in light intensity results in the difference in light energy applied to each pixel. Therefore, the amount of light energy applied to one pixel by the excitation light Le2 is 1/10 of the amount of light energy applied to one pixel by the excitation light Le. Note that the amount of light energy imparted to one pixel by the excitation light Le2 is preferably equal to or less than ½ of the amount of light energy imparted to one pixel by the excitation light Le2.

  As is clear from the above description, the image information acquisition apparatus according to the present embodiment detects the intensity of the stimulated emission light emitted by the main and sub-scanning of the stimulable phosphor sheet with the excitation light. In the main scanning line, the stimulated emission light can be generated by excitation, but the excitation light Le2 having a low light intensity is irradiated to detect the intensity of the emitted stimulated emission light Kh2, and the even-numbered main scanning line is detected. In the line, by irradiating excitation light Le with high light intensity and detecting the intensity of the stimulated emitted light Kh, the light intensity of the stimulated emitted light Kh is less than or equal to a preset light intensity threshold S1. In a certain pixel, the detected value of the light intensity of the stimulated emission light Kh is used as the pixel value. When the light intensity of the stimulated emission light Kh is larger than the light intensity threshold value S1, the detection value of the light intensity of the stimulated emission light Kh2 is detected. Multiplied by the multiplication factor K Because it uses as a pixel value, using a user-friendly PMT31, a stimulable phosphor radiation image information recorded on the sheet can be obtained over a wide dynamic range than the dynamic range of PMT31. In addition, since the site | part which irradiates excitation light Le is a site | part which is not irradiated with excitation light Le2, even if the amount of radiographic image information currently recorded on the site | part is very small, acquiring image information accurately. Can do.

  An apparatus that scans odd-numbered main scanning lines with the excitation light Le2 and scans even-numbered main scanning lines with the excitation light Le only adds some changes to the existing main / sub-scanning type image information acquisition apparatus. It can be realized at low cost.

  In the present embodiment, as shown in FIG. 5A, the odd-numbered main scanning line is irradiated with the excitation light Le2, and the even-numbered main scanning line is irradiated with the excitation light Le. For example, the odd-numbered main scanning line may be irradiated with the excitation light Le, and the even-numbered main scanning line may be irradiated with the excitation light Le2.

  Further, as shown in FIG. 5B, the sub-scan may be performed so that a beam of the next even-numbered main scanning line overlaps the beam of the odd-numbered main scanning line. In this case, the resolution in the sub-scanning direction is improved. When a part of the beams overlaps, it is desirable to scan the odd-numbered main scanning line with the excitation light Le2 having a low light intensity and scan the even-numbered main scanning line with the excitation light Le having a high light intensity. .

  Further, as shown in FIG. 6C, a lens is inserted in the optical path of the excitation light Le, and the beam shape of the excitation light Le is an ellipse that is long in the sub-scanning direction and includes the odd-numbered main scanning line regions. The even-numbered main scanning line may be scanned, and in this case, the radiation energy remaining in the odd line region irradiated with the excitation light Le2 having a low excitation efficiency is also emitted as the stimulated emission light. The radiation destination energy recorded in the stimulable phosphor sheet 20 can be detected efficiently. When the beam diameter is increased, it is desirable to increase the amount of laser light emitted from the laser light source 11 so that the light intensity per unit area does not decrease.

  Further, it is not always necessary to alternately scan the odd-numbered main scanning lines and the even-numbered main scanning lines. For example, first, all the odd-numbered main scanning lines are scanned with the excitation light Le2, and then the excitation light is scanned. All of the even-numbered main scanning lines may be scanned by Le.

  The excitation light is not necessarily spot-like light, and may be line-like light extending in the main scanning direction, and two-dimensional scanning is performed by alternately irradiating excitation light for each main scanning line. It can be carried out. When line-shaped light is used as excitation light, it is preferable to use a line-shaped photodetector extending in the main scanning direction, such as a line CCD, as the photodetector.

  Note that the threshold value S1 stored in the memory 44 in advance may be appropriately selected from the specifications of the photodetector to be used. In addition, a constant is used as the multiplication factor K in order to simplify the explanation, but it is not limited to this. For example, a look based on the relationship between the radiation dose and the stimulated emission light Kh2 obtained by measurement is used. The multiplication rate K may be obtained from an up table or the like.

Schematic configuration diagram of an information acquisition apparatus according to an embodiment of the present invention External view of information acquisition device The figure which shows the relationship between the light intensity of the excitation light with which the stimulable phosphor sheet is irradiated and the generated stimulated emission light Schematic diagram showing the relationship between radiation intensity and stimulated emission light intensity Illustration of the beam shape of excitation light

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Laser light source 14 Attenuator 16 Polygon motor 17 Polygon mirror 18 f (theta) lens 19 Reflector 20 Storage phosphor sheet 21 Sheet sample holder 22 Sample stage 30 Light guide 30a Incident end 30b Emission end 31 PMT
32 Excitation light cut filter 40 A / D converter 41 Line buffer 42 Image processing unit 43a, 43b Image buffer 44 Memory 50 Display unit 60 Control unit 61 Input unit 100 Optical system 200 Recording medium transport unit 300 Detection unit 400 Signal processing unit 500 Case 800 Image information acquisition device Le, Le2 Excitation light Kh, Kh2 Stimulated emission light

Claims (4)

The predetermined area of the stimulable phosphor sheet on which the radiographic image is recorded is irradiated with excitation light, the intensity of light emitted from the predetermined area is detected by the irradiation, and the predetermined area is based on the detected light intensity An image information acquisition method for acquiring image information held by
A part of the predetermined region is irradiated with first excitation light to give first light energy, and the intensity of the first light emitted from the predetermined region is detected by the application of the first light energy. Then, the second excitation light is irradiated to a region including the remaining part of the predetermined region to give a second light energy having a light energy amount different from the first light energy, The intensity of the second light emitted from the predetermined area is detected by applying light energy, and the predetermined area is held based on the detected intensity of the first light and the intensity of the second light. An image information acquisition method characterized by acquiring acquired image information. The predetermined area of the stimulable phosphor sheet on which the radiographic image is recorded is irradiated with excitation light, the intensity of light emitted from the predetermined area is detected by the irradiation, and the predetermined area is based on the detected light intensity An image information acquisition device that acquires image information held by
The first excitation light is irradiated to a part of the predetermined region to give the first light energy, and then the second excitation light is irradiated to the region including the remaining part of the predetermined region. Excitation light irradiation means for applying a second light energy having a light energy amount different from the light energy of 1,
Light for detecting the intensity of the first light emitted from the predetermined area by the application of the first light energy and the intensity of the second light emitted from the predetermined area by the application of the second light energy. Detecting means; and image information generating means for acquiring image information held in the predetermined area based on the intensity of the first light and the intensity of the second light detected by the light detecting means. An image information acquisition apparatus characterized by that.   The excitation light irradiating means is configured to perform main and sub scanning of the stimulable phosphor sheet with the beam-shaped first excitation light and the beam-shaped second excitation light, and with the first excitation light. 3. The image information acquisition apparatus according to claim 2, wherein the odd-numbered main scanning line is scanned, and the even-numbered main scanning line is scanned with the second excitation light.   The image information acquisition according to claim 3, wherein a beam diameter of the excitation light that gives a large light energy is larger than a beam diameter of the other excitation light among the first excitation light and the second excitation light. apparatus.

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