JP2004128717A - Radiation image information reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of a charge overflow in a charge transfer path of a CCD sensor in a radiation image information reading apparatus using the CCD sensor as a photodetector for detecting a stimulated luminescence light. <P>SOLUTION: In the radiation image information reading apparatus 10 using the CCD sensor as a photodetector for detecting a stimulated luminescence light emitted from a storage phosphor sheet IP, an overflow level of the CCD sensor is controlled by a CCD control unit 4, on the basis of at least any one of a radiation image photographing condition such as X-ray exposure dose on the storage phosphor sheet IP controlled by an X-ray tube controller 3, a reading condition of the accumulated luminescence light, and image processing condition to be applied to the read image signal. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention irradiates a stimulable phosphor sheet on which radiographic image information is accumulated and recorded with excitation light, thereby photoelectrically reading the photostimulated luminescence emitted from the sheet and indicating the radiographic image information. In particular, the present invention relates to a radiation image information reading apparatus using a CCD sensor as a photodetector for detecting stimulated emission light.
[0002]
[Prior art]
Conventionally, a part of this radiation energy is accumulated when irradiated with radiation, and then, when irradiated with excitation light such as visible light or laser light, a stimulable phosphor (stimulated phosphor) that exhibits stimulated luminescence according to the accumulated radiation energy. Exhaustible phosphors) are known, and radiation image recording / reproducing systems using a stimulable phosphor sheet obtained by laminating this stimulable phosphor on a support have been widely put into practical use.
[0003]
This radiographic image recording / reproducing system accumulates and records radiographic image information of a subject on the stimulable phosphor sheet by irradiating the stimulable phosphor sheet with radiation that has passed through a subject such as a human body, and then a laser beam. The sheet is scanned two-dimensionally with excitation light such as to generate stimulated emission light from a portion irradiated with the excitation light, and the stimulated emission light is read by a photoelectric reading means to obtain an image signal indicating the radiographic image information. To get.
[0004]
The image signal obtained by this system is subjected to image processing such as gradation processing and frequency processing suitable for observation interpretation, and the radiological image carried by the system is reproduced and recorded on the film as a diagnostic visible image. Or used for display on a CRT image display device or the like.
[0005]
Here, in the radiographic image information reading apparatus used in the radiographic image recording / reproducing system described above, photoelectric reading means (photodetection) is used from the viewpoint of shortening the reading time of the photostimulated luminescence light, downsizing the apparatus, and reducing the cost. It has been proposed to apply a line sensor comprising a CCD as a device. Patent Document 1 shows an example of a radiation image information reading apparatus that obtains an image signal indicating radiation image information from a stimulable phosphor sheet in this manner.
[0006]
By the way, in the CCD sensors such as the CCD line sensor and the CCD area sensor described above, the charge accumulation time is generally determined by a transfer gate for controlling the charge transfer from the photoelectric conversion unit constituted by a photodiode to the charge transfer path (CCD). A period of one line or one frame is determined. A CCD sensor having an electronic shutter function has a clear gate in addition to the transfer gate, and the charge accumulation time and the period of one line or one frame can be set separately by this clear gate.
[0007]
In addition, when an excessive amount of light is incident on the photoelectric conversion unit and an excessive charge exceeding the saturation charge is generated, an overflow gate is provided to prevent the charge from passing over the transfer gate and flowing into the charge transfer path. Is provided. Then, the electric charge exceeding the overflow gate is swept out to the overflow drain. FIG. 4 explains the concept of this overflow gate. In the figure, PD is one photoelectric conversion unit (pixel) made of a photodiode, TG is a transfer gate, OFG is an overflow gate, CCD is a charge transfer path, and OFD is an overflow drain, (1), (2 (3) and (3) respectively show the states at the time of charge accumulation, charge read-out, and overflow. Since the overflow function can be performed by setting the potential of the clear gate low level higher than the transfer gate low level, the clear gate may also serve as the overflow gate.
[0008]
In the above configuration, when the charge storage capacity of the photodiode that is the photoelectric conversion unit exceeds the charge storage capacity of the charge transfer path formed by the CCD, excessive light is incident on the photoelectric conversion unit of a certain pixel and a large amount of charge is generated. When generated, a large amount of charge that could not be swept out to the overflow drain flows into the charge transfer path. If these charges exceed the storage capacity of the charge transfer path, the charges flow to another photoelectric conversion unit or transfer unit pixel. In this case, the charge spreads to pixels other than the pixels where excessive light is incident, and appropriate information held by these pixels is also destroyed.
[0009]
In order to prevent the above problems, the charge storage capacity of the photoelectric conversion unit is preferably smaller than the charge storage capacity of the charge transfer path. However, in the above-described radiographic image information reading apparatus, it is necessary to efficiently detect weak stimulated emission light, and for this purpose, a CCD sensor having a large photoelectric conversion area is used. Therefore, generally, the charge storage capacity of the photoelectric conversion unit becomes larger than the charge storage capacity of the charge transfer path, and the above problem occurs.
[0010]
Japanese Patent Application Laid-Open No. 2005-228561 discloses a technique in which an apparatus that reads an original image by irradiating an original with illumination light reduces the amount of illumination light again and rereads the pixel in which overflow has occurred. However, since reading of radiation image information is so-called destructive reading, it is impossible to read it again.
[0011]
Therefore, in reading radiographic image information, the maximum light amount incident on the CCD sensor is assumed in advance, and when the light amount exceeding that is incident, the low level of the overflow gate is set so that all excess charges are swept out to the overflow drain. It is also possible to set. However, in reading a document image, which is premised on the technique of Patent Document 2, it is easy to assume the maximum amount of light incident on the CCD sensor in advance, but in reading radiographic image information other than the region of interest (for example, It has become extremely difficult to assume the amount of stimulated emission light generated from the so-called blank portion where the radiation reaches the stimulable phosphor sheet without passing through the subject.
[0012]
Considering such circumstances, the low level applied voltage V of the overflow gate shown in (2) of FIG. _{OFG L} Is set to be higher (that is, from +4.5 V to +6.0 V in the example in the figure), and the amount of charge flowing in the charge transfer path can be suppressed to be always smaller than the capacity of the transfer path. However, if this is done, the variation in the saturation charge of the photodiode in the photoelectric conversion section becomes significant, and the output saturation characteristics under the amount of stimulated emission necessary for image formation are governed by the variation in the saturation charge of the photodiode. As a result, the dynamic range of the output becomes narrow and it becomes impossible to reproduce a high-quality radiographic image.
[0013]
The present invention has been made in view of the above circumstances, and uses radiographic image information capable of preventing charge overflow in the charge transfer path after using a CCD sensor as a photodetector for detecting stimulated emission light. An object is to provide a reader.
[0014]
[Patent Document 1]
Japanese Patent Laid-Open No. 1-1101540
[0015]
[Patent Document 2]
JP-A-8-130608
[0016]
[Means for Solving the Problems]
The radiological image information reading apparatus according to the present invention, as described above,
Radiation image information for obtaining an image signal indicating the radiation image information by irradiating the stimulable phosphor sheet on which radiation image information is accumulated and recorded with excitation light and detecting the stimulated emission light emitted from the sheet with a CCD sensor In the reading device,
The overflow level of the CCD sensor is based on at least one of a radiographic image capturing condition on the stimulable phosphor sheet, a reading condition of the stimulating light, and an image processing condition applied to the image signal. And a control means for controlling.
[0017]
More specifically, the control means generally makes the overflow level deeper as the above-mentioned conditions are the conditions that the charge accumulation amount in the CCD sensor is larger (the low level applied voltage V of the overflow gate). _{OFG L} To be higher).
[0018]
【The invention's effect】
As described above with reference to (2) of FIG. 4, the low level applied voltage V of the overflow gate of the CCD sensor. _{OFG L} If the value is made higher and the overflow level is made deeper, the amount of charge flowing in the charge transfer path can be reduced. On the contrary, if the overflow level is made shallower, the dynamic range of the output of the CCD sensor can be widened.
[0019]
On the other hand, if the radiographic image capturing conditions on the stimulable phosphor sheet, the reading conditions of the stimulated emission light, and the image processing conditions to be applied to the image signal are known, the stimulable phosphor sheet to be read is free of radiation. To know whether or not there is a possibility of generating a particularly large amount of stimulated emission light by including a part, that is, whether or not there is a possibility of causing the above-described charge overflow in the CCD sensor. Can do.
[0020]
Therefore, if the storage phosphor sheet to be read has a possibility of generating a large amount of photostimulated luminescence, by setting the overflow level deeper, the dynamic range may be sacrificed to some extent. The occurrence of overflow can be reliably prevented. On the other hand, if the storage phosphor sheet to be read is not particularly likely to generate a large amount of photostimulated luminescent light, a wider dynamic range should be secured by setting the overflow level shallower. Is possible.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0022]
FIG. 1 shows a schematic configuration of a radiographic image information recording / reading apparatus according to an embodiment of the present invention. FIG. 2 shows an overflow level control performed for a CCD sensor in the radiographic image information recording / reading apparatus. It shows the flow.
[0023]
This radiographic image information recording / reading apparatus includes a reader control unit 1 and a radiographic image information recording / reading apparatus main body 10 whose operation is controlled by the reader control unit 1. The reader control unit 1 is connected to a recording / reading apparatus main body 10 and to a system control unit 2, and an X-ray tube control unit 3 is connected to the system control unit 2. The X-ray tube control unit 3 controls driving of a radiation source (X-ray source) 20 that emits radiation for recording (imaging) a radiation image in the radiation image information recording / reading device body 10.
[0024]
First, the radiation image information recording / reading apparatus main body 10 will be described in detail with reference to FIG. This apparatus basically irradiates the radiation image recording unit 12 for temporarily recording the radiation image information of the subject 18 such as a human body on the stimulable phosphor sheet IP, and the stimulable phosphor sheet IP with the excitation light L, and The reading unit 14 that photoelectrically reads the stimulated emission light R emitted according to the intensity of the accumulated radiation energy, and the radiation energy remaining in the stimulable phosphor sheet IP after the radiation image information is read. And an erasing unit 16 for discharging the.
[0025]
The radiation image recording unit 12 includes an X-ray source 20 that emits radiation S and a radiation-transmissive imaging table 22 that holds the subject 18 at a predetermined position. A phototimer 23 for controlling the irradiation time by integrating the radiation dose and a grid 24 for removing scattered radiation are disposed behind the imaging table 22, and the stimulable phosphor sheet is further behind the grid 24. The IP is fixed at a predetermined shooting position.
[0026]
A laser diode array 32 that emits excitation light L in a linear shape is disposed on the upper portion of the housing 30 that constitutes the reading unit 14. The excitation light L that is emitted from the laser diode array 32 and spreads in one direction (a direction perpendicular to the paper surface in the drawing) is reflected by the mirror 34 fixed to the housing 30 and is formed on the stimulable phosphor sheet IP. Are linearly irradiated in the main scanning direction (horizontal direction).
[0027]
Further, on the lower part of the housing 30 constituting the reading unit 14, the stimulated emission light R emitted from the linear portion of the stimulable phosphor sheet IP irradiated with the excitation light L is emitted from the condensing lens array 36 and CCD line sensors 40a to 40c that receive light through the prism 38 and convert them into electrical signals are provided. The prism 38 distributes the stimulated emission light R to the CCD line sensors 40 a and 40 c disposed on the side of the housing 30 and the CCD line sensor 40 b disposed on the lower portion of the housing 30.
[0028]
Each of the CCD line sensors 40a to 40c arranged in a staggered pattern is configured by arranging a large number of photoelectric conversion units in the main scanning direction. The CCD line sensors 40a to 40c are not necessarily configured with three. These CCD line sensors 40a to 40c are equipped with a filter (not shown) that transmits the stimulated emission light R emitted from the stimulable phosphor sheet IP and blocks external light including the excitation light L. Yes.
[0029]
The erasing unit 16 includes a housing 50 and is fixed to the upper portion of the housing 30 of the reading unit 14. The casing 50 includes a plurality of fluorescent lamps 52 (1) to 52 (n) extending in the main scanning direction of the stimulable phosphor sheet IP and irradiating the stimulable phosphor sheet IP with the erasing light Q. A lighting circuit 54 for lighting these fluorescent lamps 52 (1) to 52 (n) is housed.
[0030]
Behind the reading unit 14 and the erasing unit 16 are arranged a guide rail 60 extending in the vertical direction and a belt 68 wound around a driving pulley 64 and a driven pulley 66 rotated by a sub-scanning motor 62. Yes. The housing 30 of the reading unit 14 engages with the guide rail 60 so as to be movable along the guide rail 60 and is connected to the belt 68. That is, the reading unit 14 and the erasing unit 16 integrated therewith move in the sub-scanning direction, that is, the arrow Y1 or Y2 direction while being guided by the guide rail 60 by the belt 68 driven by the rotation of the sub-scanning motor 62.
[0031]
Hereinafter, basic operations and effects of the radiation image information recording / reading apparatus main body 10 will be described. As shown in FIG. 1, the subject 18 is positioned at a predetermined position of the radiation image recording unit 12 in the radiation image information recording / reading apparatus body 10, and then the X-ray source 20 is driven to irradiate the subject 18 with the radiation S. The radiation S transmitted through the subject 18 reaches the stimulable phosphor sheet IP via the phototimer 23 and the grid 24, and the radiation image information of the subject 18 is recorded on the sheet IP. Note that the phototimer 23 integrates the dose of the radiation S and controls the driving of the X-ray source 20 according to the integrated value.
[0032]
Next, the reading unit 14 descends from the upper end position along the guide rail 60 in the direction of the arrow Y1, and the radiation image information is read. The excitation light L emitted from the laser diode array 32 is reflected by the mirror 34 and irradiated linearly in the main scanning direction of the stimulable phosphor sheet IP. From the part of the stimulable phosphor sheet IP irradiated with the excitation light L, the stimulated emission light R corresponding to the stored radiation image information is emitted. The stimulated emission light R is detected by the CCD line sensors 40a to 40c via the condenser lens array 36 and the prism 38, and is converted into an electric signal. Then, the CCD line sensors 40a to 40c move in the arrow Y direction to perform sub-scanning of the excitation light L, and the radiation image information recorded on the stimulable phosphor sheet IP is read two-dimensionally.
[0033]
When the reading unit 14 moves to the lower end position and the reading of the radiation image information is completed, the reading unit 14 rises along the guide rail 60 in the arrow Y2 direction. At this time as well, the reading operation, that is, the irradiation of the stimulable phosphor sheet IP with the excitation light L and the detection of the stimulated emission light R are performed. This detects the level of the radiation energy remaining in the stimulable phosphor sheet IP. Therefore, by increasing the rotation speed of the sub-scanning motor 62, the sub-scanning speed is set to twice that when reading the radiation image information (when the reading unit 14 is lowered). Accordingly, in this case, the number of read pixels is the same in the main scanning direction and ½ in the sub-scanning direction as compared to when reading radiation image information.
[0034]
When the reading unit 14 moves to the upper end position, the erasing unit 16 then descends in the direction of the arrow Y1, during which the erasing light Q emitted from the fluorescent lamps 52 (1) to 52 (n) is stored in the stimulable phosphor sheet IP. Irradiate the entire surface. As a result, the radiation energy remaining in the stimulable phosphor sheet IP is released, and the sheet IP becomes ready to be used for the next imaging.
[0035]
The analog read image signals output from the CCD line sensors 40a to 40c are input to an A / D converter via an amplifier and a sample hold circuit (not shown) and converted from analog signals to digital signals. The digital read image signal is input to the image processing unit 7 included in the system control unit 2 shown in FIG.
[0036]
In the image processing unit 7 shown in FIG. 1, image processing such as contour enhancement, noise removal, size conversion / rotation, and the like is performed on the input radiation image data. Thereafter, the radiation image data is transferred to an image processing apparatus such as an IIP (Image Information Processor) (not shown), and after further image processing, a recording medium such as a photographic photosensitive material or a CRT (Cathode Ray Tube) or the like. The radiation image carried by the data DC is output as a visible image.
[0037]
Further, the CCD control unit 4 of the reader control unit 1 shown in FIG. 1 controls the operation of the CCD line sensors 40a to 40c including control of an overflow level described later. The head control unit 5 controls the operation of the scanner head SH including the above-described reading unit 14 and erasing unit 16, and the LD control unit 6 controls the operation of the laser diode array 32.
[0038]
On the other hand, the imaging control unit 8 of the system control unit 2 controls the operation of the X-ray tube control unit 3 that controls the driving of the X-ray source 20 as described above.
[0039]
Next, the control by the system control unit 2, the X-ray tube control unit 3 and the CCD control unit 4 will be described in more detail with reference to FIG. In FIG. 2, processing steps performed by the respective control units are shown below the respective control units 2 to 4. First, the system control unit 2 sets shooting conditions, reading conditions of the stimulated emission light, image processing conditions in the image processing unit 7 and the like based on information input from a console (not shown) or automatic determination (step) P1). Here, as an example, the tube voltage of the X-ray tube, the tube current and the exposure time, the type of the stimulable phosphor sheet IP, the imaging region and imaging dose related to the subject 18, the reading mode such as the number of pixels and the reading speed, and the EDR Conditions (reading operations for grasping accumulated radiation image information, so-called pre-reading conditions, which are performed before performing a reading operation for obtaining an image signal for reproducing a radiation image) are set.
[0040]
The system control unit 2 sends information indicating the set tube voltage, tube current, and exposure time of the X-ray tube to the X-ray tube control unit 3, and the X-ray tube control unit 3 performs this information in step P5. Based on the above, the tube voltage, tube current and exposure time of the X-ray source 20 are set. When this setting is completed, the X-ray tube control unit 3 inputs a signal indicating completion of preparation for exposure to the system control unit 2 in step P6.
[0041]
In step P2, the system control unit 2 calculates an appropriate overflow gate (OFG) level in the CCD line sensors 40a to 40c based on the tube voltage, the tube current, and the exposure time. This calculation is based on the overflow voltage when it is assumed from the tube voltage, the tube current and the exposure time that the amount of the stimulated emission light R emitted from the stimulable phosphor sheet IP is larger than a predetermined threshold value. Low level applied voltage V _{OFG L} The applied voltage V in the other normal cases. _{OFG L} Is made lower.
[0042]
The system control unit 2 calculates the calculated applied voltage V _{OFG L} Is input to the CCD controller 4, and in step P7, the CCD controller 4 applies the overflow gate low level applied voltage V as indicated by this information. _{OFG L} Is applied to the CCD line sensors 40a to 40c. When this voltage application is completed, the CCD controller 4 inputs a signal indicating completion of exposure preparation to the system controller 2 in step P8.
[0043]
When the system control unit 2 confirms in step 3 that signals indicating completion of exposure preparation are input from the X-ray tube control unit 3 and the CCD control unit 4, the system control unit 2 next drives the X-ray source 20 in step P4. A signal to be transmitted is sent to the X-ray tube control unit 3 to perform X-ray exposure, that is, imaging. Next, in step P9, the system control unit 2 starts the above-described reading operation by the recording / reading device body 10. As a result, the CCD controller 4 starts driving the CCD line sensors 40a to 40c in step P10.
[0044]
Next, the setting of the overflow gate level will be described in detail with reference to FIG. (1) in the figure shows the low level applied voltage V of the overflow gate. _{OFG L} And the relationship between the saturation voltages of several photodiodes constituting each charge storage section (pixel) of the CCD line sensors 40a to 40c. In FIG. 1A, OFG2 indicates a low level applied voltage V of the overflow gate. _{OFG L} Is higher (ie, the overflow gate level is deeper), OFG1 shows the low level applied voltage V of the overflow gate. _{OFG L} Is lower (ie, the overflow gate level is shallower).
[0045]
Here, the low level applied voltage V of the overflow gate is applied to the CCD line sensors 40a to 40c. _{OFG L} Is applied, the saturation voltage of the photodiode of each pixel becomes the applied voltage V _{OFG L} It is reduced uniformly according to the value of. That is, the charges shown in white in (2) and (3) in the figure are discarded to the overflow drain (OFD) through the overflow gate.
[0046]
As shown in FIG. 2 (2), the level of OFG2 set when the stimulated emission light is assumed to be a large amount of light is determined by the capacitance of the pixel having the maximum photodiode capacitance, the CCD charge transfer path. The level is set to be equal to or less than the capacity. As a result, no matter how large the amount of stimulated emission light R is incident on the photodiode, the charge exceeding the capacity of the charge transfer path will not be accumulated in the photodiode, resulting in the charge overflow as described above. Is reliably prevented.
[0047]
However, in this case, the effective range for image recording is determined by the capacity of the pixel having the smallest photodiode capacity as indicated by (2) in FIG. , {Circle over (3)} is a loss. That is, in this case, the dynamic range for detecting the stimulated emission light is as narrow as DR2. If the outputs of the CCD line sensors 40a to 40c are used after A / D conversion as they are, the outputs of the pixels that have received signals other than the effective image area vary, and appear as abnormal images such as stripes in the reproduced radiation image. This phenomenon can be solved by, for example, matching the upper limit of the dynamic range to the upper limit (for example, 4V) of the input range of the A / D converter and clipping the output beyond that to the upper limit of 4V or the like. .
[0048]
On the other hand, as shown in FIG. 3 (3), the level of OFG1 that is set in the normal case where the stimulated emission light is not assumed to be particularly large is the capacitance of the pixel with the smallest photodiode capacitance. The level is aligned with the upper limit of the range (5) effective for recording. As a result, the entire capacity of the CCD charge transfer path is used for the signal in the effective image range, and the loss of the CCD capacity is eliminated, so that the dynamic range of the detection of the stimulated emission light is widely secured as DR1. In this case, however, as shown in (6) in the figure, when a charge that does not fit in the CCD charge transfer path is generated in the photodiode, a charge overflow may occur. In order to prevent this phenomenon, it is desirable to provide guidance, display, or the like that restricts the maximum exposure amount of X-rays to the user in the radiation image information recording / reading apparatus.
[0049]
As described above, the embodiment in which the overflow gate level is selectively set to one of the two types has been described. However, the level setting is not limited to such two steps, and charge overflow prevention and wide dynamics are possible. In consideration of both securing the range, the overflow gate level may be set stepwise to three or more, or may be set to change continuously.
[0050]
In the above embodiment, the overflow gate level is controlled based on the X-ray tube voltage, tube current, and exposure time, which is one of the imaging conditions. However, in the present invention, other imaging conditions, The overflow gate level may be controlled based on the radiation image information reading condition from the stimulable phosphor sheet, the image processing condition for the image signal obtained by the reading, and the like.
[0051]
For example, other imaging conditions include a body part such as a human body, but in a side-shot image, the energy level of radiation from the unexposed part is usually extremely high, and on the other hand, the chest is taken in front In the obtained image, the energy level of radiation from the unexposed portion is weaker than the above. Therefore, for the former, the low level applied voltage V of the overflow gate _{OFG L} To prevent charge overflow, and for the latter, the applied voltage V _{OFG L} Can be set lower to ensure a wide dynamic range.
[0052]
Considering the reading speed which is one of the reading conditions, the amount of stimulated emission light incident on the CCD sensor is generally larger in the low-speed reading than in the high-speed reading. Therefore, for the former, the low level applied voltage V of the overflow gate _OFGL To prevent charge overflow, and for the latter, the applied voltage V _{OFG L} Can be set lower to ensure a wide dynamic range.
[0053]
In addition, the charge accumulation time of the CCD sensor may be changed while the reading speed is kept constant. In this case, the amount of charge generated by the photodiode of the CCD sensor is longer when the charge accumulation time is longer. Greater than the short case. Therefore, for the former, the low level applied voltage V of the overflow gate _{OFG L} To prevent charge overflow, and for the latter, the applied voltage V _{OFG L} Can be set lower to ensure a wide dynamic range.
[0054]
Furthermore, one of the imaging conditions is the type of stimulable phosphor sheet, but the stimulable phosphor sheet with high radiation sensitivity has the same level of radiation exposure as the less sensitive stimulable phosphor sheet. The amount of emitted light is larger. In addition, the stimulable phosphor sheet with high stimuli emission directivity even though the sensitivity is constant has a high concentration efficiency of the stimulated emission light, and therefore the same radiation exposure as compared with the stimulable phosphor sheet with low directivity. The amount of stimulated light emission with respect to the amount of radiation is greater. Therefore, for such a highly sensitive or highly directional storage phosphor sheet, a low level applied voltage V of the overflow gate V _{OFG L} To prevent charge overflow, and for the storage phosphor sheet having lower sensitivity or lower directivity than the applied voltage V _{OFG L} Can be set lower to ensure a wide dynamic range.
[0055]
In the present invention, the overflow level may be controlled based on a combination of two or more of the radiographic image capturing conditions, the photostimulated emission light reading conditions, and the image processing conditions applied to the read image signal. Good.
[0056]
Furthermore, the present invention can be applied not only to the radiographic image information recording / reading apparatus described above but also to a read-only apparatus, and in that case, the above-described effects of the present invention can be achieved.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a radiographic image information recording / reading apparatus according to an embodiment of the present invention;
FIG. 2 is a flowchart showing a control flow in the radiographic image information recording / reading apparatus of FIG. 1;
3 is a side view showing a part of the radiation image information recording / reading apparatus of FIG. 1. FIG.
FIG. 4 is an explanatory diagram for explaining the action of an overflow gate.
FIG. 5 is an explanatory diagram for explaining the control of the overflow gate level in the radiographic image information recording / reading apparatus of FIG.
[Explanation of symbols]
1 Reader control unit
2 System controller
3 X-ray tube control unit
4 CCD controller
5 Head controller
6 LD controller
7 Image processing section
8 Shooting control unit
14 Reading unit
20 X-ray source
40a-40c CCD line sensor
IP storage phosphor sheet
L Excitation light
R photostimulated light

Claims (2)

Radiation image information for obtaining an image signal indicating the radiation image information by irradiating the stimulable phosphor sheet on which radiation image information is accumulated and recorded with excitation light and detecting the stimulated emission light emitted from the sheet with a CCD sensor In the reading device,
The overflow level of the CCD sensor is based on at least one of a radiographic image capturing condition on the stimulable phosphor sheet, a reading condition of the stimulating light, and an image processing condition applied to the image signal. A radiation image information reading apparatus comprising a control means for controlling the radiation image information. 2. The radiological image information reading apparatus according to claim 1, wherein the control means makes the overflow level deeper as the condition is such that the charge accumulation amount in the CCD sensor is larger. .

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