JP2007057946A - Image input device and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image input device that detects and inputs radiation image information such that even when a small cassette is used, sensitivity can be easily and accurately corrected, and to provide an image input method. <P>SOLUTION: This image input device detects radiation image information by a detector and inputs image information based upon the detected radiation image. In this case, the detector detects the radiation image formed when a fixed quantity of radiation is emitted in order to correct the sensitivity of the detector. A correction value for the sensitivity of the detector is automatically calculated so that the signal value of the detected radiation image has a predetermined value. When the correction value for the sensitivity is changed for calculating the correction value for the sensitivity, the detection of the radiation image information by the detector is stopped in order to ensure a stabilizing time for a factor involved in the change. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image input apparatus and an image input method for inputting radiation image information mainly used in the medical field.

  2. Description of the Related Art An image input apparatus is known that irradiates a subject with radiation from a radiation generation apparatus for disease diagnosis or the like, reads a radiation image of radiation transmitted through the subject, and inputs image information. In such an image input device, a photostimulator (hereinafter sometimes referred to as “PMT”) that collects photostimulated light generated by scanning laser light on a photostimulable phosphor plate that stores radiation image information. There is a system (CR type) that photoelectrically converts it into an electrical signal. For example, when PMT sensitivity correction is performed in a CR type image input device, an ideal signal value is output from PMT voltage and light quantity characteristic data and a PMT signal value when X-ray imaging is performed for sensitivity correction. The offset value (voltage setting value of PMT) was calculated by calculation (see Patent Documents 1 to 4 below).

  Regarding the above-described image input device, the present inventor previously disclosed in Japanese Patent Application Laid-Open No. 2004-259542 that the radiation is irradiated with a certain dose for correcting the sensitivity of a detector such as PMT, and the ideal value of the signal value at that time is as follows. To obtain the offset value so that the signal value when the sensitivity correction value is changed as the offset value is the same as the ideal value, and use it as the sensitivity correction value, so that the sensitivity correction can be performed easily and accurately. Proposed.

  Here, sensitivity correction (sensitivity calibration) is when a certain dose (mR) is irradiated to the plate surface for different sensitivities (emission luminance for a certain dose) for each type of stimulable phosphor plate. In other words, the correction is always performed so that the same signal value is obtained. As an image reading method, the stimulated emission light after scanning with laser light is condensed by a PMT (photomultiplier). The amount of current is determined by the amount of light and the voltage applied to the PMT (specifically, the voltage applied to the bleeder circuit). Determined. Even if the same dose is given, the amount of light taken into the PMT from the stimulable phosphor plate varies. As the fluctuation factors, there are sensitivity differences due to different types of stimulable phosphor plates and PMT sensitivity differences, so that the output current is made constant when the same dose is applied by controlling the applied voltage. Perform correction (sensitivity correction).

  Conventionally, by performing sensitivity calibration, the applied voltage corresponding to the photostimulable phosphor plate and the PMT is used at the time of actual image reading, and when the same dose and the same plate are irradiated with X-rays, the signal value is always obtained. A constant value is set. The types of photostimulable phosphor plates are different constituent materials, different structures, different types of stimulable phosphors, different structures due to coating and vapor deposition, and the thickness and materials of the cassette front plate (carbon materials, acrylic materials, etc.) ) Due to differences.

  Patent Document 1 describes a method of performing sensitivity calibration within one exposure after using a normal reading operation. While performing the reading operation, the applied voltage of the PMT is changed to obtain an acquired signal value. In this method, the applied voltage is obtained by searching for a place where the theoretical values that can be obtained from the irradiation dose match. The problems with this method are that it takes a stable time when the applied voltage is changed, and the applied voltage is changed while performing the reading operation. The sensitivity correction value may not be determined.

  For example, in the currently used high voltage power supply capable of generating “0 to 1000 V”, the required stabilization time to 90% rise is 50 ms, and the required stabilization time to 90% fall is 200 ms. In starting up the high voltage power supply, when changing the full range, it is necessary to take a margin and take a stable time of 100 ms rise and 400 ms fall. In Patent Document 1, it is possible to cope with a stable time of 50 ms rise and 400 ms fall by restricting voltage transition in the 1/32 range instead of the full range.

Since the time required for one line at the time of image reading is about 5 ms, a stabilization time of 20 lines is required when the voltage of the high voltage power supply is changed. In a small size cassette (for example, a dental 15 × 30 cm cassette) in the sub-scanning direction of 15 cm, if a pixel size of 175 μm is read with one line, 860 lines are required. If the data of 6 polygon planes is averaged and used when reading image data, the number of sub-scanning lines required for one high-voltage power supply setting is 26, so that 33 comparison operations can be performed. For example, if the set voltage is set in three stages, only 11 comparison operations can be performed per stage, which is a strict condition for accurate sensitivity correction.
JP 2004-77709 A Japanese Patent Laid-Open No. 03-132644 Japanese Patent Laid-Open No. 05-122518 JP 2002-156713 A

  SUMMARY OF THE INVENTION In view of the above-described problems of the prior art, the present invention is an image input device that detects and inputs radiation image information that can perform sensitivity correction easily and accurately even when a small-size cassette is used. An object of the present invention is to provide an image input method.

  In order to achieve the above object, an image input apparatus according to the present invention is an image input apparatus that includes detection means for detecting radiation image information, and that inputs image information based on the detected radiation image, A sensitivity correction unit that automatically obtains a sensitivity correction value of the detection unit such that a signal value of a radiographic image detected by the detection unit when a certain dose is given becomes a predetermined value; and the sensitivity correction value Detection stop means for stopping detection of radiation image information by the detection means in order to ensure a stable time of a factor accompanying the change when the sensitivity correction value is changed to obtain .

  According to this image input device, since the sensitivity correction value is automatically obtained so that the signal value when a fixed dose is given becomes a predetermined value, radiation irradiation for sensitivity correction is performed once, and detection is performed. The characteristic data of the means is not necessary and need not be input, and the sensitivity correction can be easily performed. Further, since calculation based on the characteristic data is not required, the accuracy of sensitivity correction is improved. Furthermore, by stopping the detection operation of the radiation image information when the sensitivity correction value is changed, it is possible to secure a stable time against the fluctuation factor accompanying the sensitivity correction, so that imaging for performing automatic calculation for sensitivity correction is performed. Even if the area is small, sufficient calculation can be performed. In this way, for example, it is possible to perform sufficient calculations for sensitivity correction even in cassettes with a small image-receiving surface, such as six-size cassettes that are relatively small in use size and special-purpose cassettes such as dental 15 × 30 cm cassettes. It becomes.

  The image input apparatus further includes a storage unit that stores an ideal value of the signal value when the fixed dose is given, and the sensitivity correction unit changes the sensitivity correction value as an offset value. The offset value that makes the signal value the same as the ideal value is obtained and used as the sensitivity correction value. Thus, the sensitivity correction value can be automatically obtained by comparing the signal value obtained by changing the offset value up and down with the ideal value and using the offset value as the sensitivity correction value.

  For example, when the detection means includes a photomultiplier having a photoelectric conversion function and a power supply for supplying a voltage to the photomultiplier, the voltage of the power supply is varied as an offset value, and the signal value is the ideal value. The offset value that is the same as the value can be used as the correction voltage value. In this case, a stabilization time is required when the voltage value of the power supply is changed. However, obtaining the correction voltage value in the direction of increasing the voltage of the power supply minimizes the stabilization time and is faster. It is preferable to perform sensitivity correction. This is in consideration of the response when the power supply voltage fluctuates.

  Further, in the image input device that obtains an offset value so that the signal value when the sensitivity correction value is changed as the offset value is the same as the ideal value and sets the sensitivity correction value, a voltage is supplied from a power source as the detection unit. Using a photomultiplier that detects emitted light from a stimulable phosphor carrying radiation image information, the offset value is a voltage value of the power source, a correction voltage value is obtained as the sensitivity correction value, and the photostimulation The correction voltage value can be obtained after changing at least one of the fixed dose and the ideal value by a predetermined magnification based on the sensitivity difference of the fluorescent phosphor. With this configuration, it is possible to obtain the sensitivity correction value even when the recording medium has a sensitivity difference.

  Further, as the detection means, the photostimulability is obtained by a relative movement between a stimulable phosphor that is supplied with voltage from a power source and carries the radiation image information and a scanning means that irradiates the stimulable phosphor with excitation light. Using a photomultiplier that detects photostimulated light emitted from a phosphor, the offset value is the voltage value of the power supply, a correction voltage value is obtained as the sensitivity correction value, and the brightness due to the difference in pitch of the relative movement The correction voltage value can be obtained by correcting the difference in signal value difference. With such a configuration, even if the light emission amount from the recording medium changes due to the difference in the relative movement pitch, the light emission amount difference can be automatically corrected.

  Another image input apparatus according to the present invention is an image input apparatus provided with detection means for detecting radiographic image information and obtaining a signal value, and inputting image information based on the detected radiographic image. Storage means for storing the ideal value of the signal value when the dose of the dose is given, a plurality of offset values when the sensitivity correction value of the detection means is changed, and the offset values obtained corresponding to the offset values A sensitivity correction unit that obtains an offset value corresponding to the ideal value from an approximate expression of the offset value and the signal value created based on the signal value, and sets the sensitivity correction value of the detection unit; and the sensitivity correction And a detection stop means for stopping the detection of the radiation image information by the detection means in order to ensure a stable time of the factor accompanying the fluctuation when the value is changed.

  According to this image input device, since a sensitivity correction value can be obtained from an approximate expression and an ideal value from a plurality of offset values and signal values, there is no need to input characteristic data of the detecting means and there is no need to input sensitivity. Correction can be performed easily. Further, since calculation based on the characteristic data is not required, the accuracy of sensitivity correction is improved. Furthermore, by stopping the detection operation of the radiation image information when the sensitivity correction value is changed, it is possible to secure a stable time against the fluctuation factor accompanying the sensitivity correction, so that imaging for performing automatic calculation for sensitivity correction is performed. Even if the area is small, sufficient calculation can be performed. In this way, for example, it is possible to perform sufficient calculations for sensitivity correction even in cassettes with a small image-receiving surface, such as six-size cassettes that are relatively small in use size and special-purpose cassettes such as dental 15 × 30 cm cassettes. It becomes.

  Another image input apparatus according to the present invention is an image input apparatus provided with detection means for detecting radiographic image information and obtaining a signal value, and inputting image information based on the detected radiographic image. Storage means for storing the ideal value of the signal value when a dose of a dose is given, and a plurality of signal values obtained corresponding to a plurality of offset values when the sensitivity correction value of the detection means is varied The signal value corresponding to the ideal value is searched, the sensitivity correction means for automatically discriminating the offset value at the signal value from the sensitivity correction value, and the factor accompanying the fluctuation when the sensitivity correction value is varied Detection stop means for stopping detection of radiation image information by the detection means in order to ensure a stable time.

  According to this image input device, the signal value corresponding to the ideal value is searched from a plurality of signal values, and the offset value at that signal value is automatically determined as the sensitivity correction value. It is unnecessary and does not require input, and sensitivity correction can be easily performed. Further, since calculation based on the characteristic data is not required, the accuracy of sensitivity correction is improved. Furthermore, by stopping the detection operation of the radiation image information when the sensitivity correction value is changed, it is possible to secure a stable time against the fluctuation factor accompanying the sensitivity correction, so that imaging for performing automatic calculation for sensitivity correction is performed. Even if the area is small, sufficient calculation can be performed. In this way, for example, it is possible to perform sufficient calculations for sensitivity correction even in cassettes with a small image-receiving surface, such as six-size cassettes that are relatively small in use size and special-purpose cassettes such as dental 15 × 30 cm cassettes. It becomes.

  In the image input device described above, when the detection unit includes a photomultiplier having a photoelectric conversion function and a power supply that supplies a voltage to the photomultiplier, the offset value is a voltage value of the power supply. The sensitivity correction value is a correction voltage value of the power source.

  In each of the image input devices described above, it is preferable that the detection stop unit is configured to stop the sub-scanning conveyance by relative movement between the detection unit and the photostimulable phosphor carrying the radiation image information. For example, when the photostimulable phosphor plate is transported for sub-scanning, the transport of the plate is stopped, or when the optical unit constituting the detection means is transported, the transport of the optical unit is stopped.

  In this case, the detection stopping means further performs at least one of stopping main scanning by the laser beam for exciting the photostimulable phosphor and turning off the laser beam. The main scanning may be stopped by stopping laser scanning for detection when the sub-scanning conveyance is stopped.

  Further, it can be configured such that the detection means resumes detection after the stable time has elapsed, and the sensitivity correction means obtains the next sensitivity correction value.

  As described above, when a sufficient stabilization time is allowed after changing the voltage of the power supply, etc., the detection operation is restarted, and when the next correction value comparison operation is started, the stabilization time of the sub-scanning conveyance speed is required May take the stabilization time of the conveyance speed. When taking the stabilization time of the transportation time, return the photostimulable phosphor plate to the area once detected to some extent, or return the optical unit of the detection means to make the distance that the transportation speed is stable enough. It is also possible to ensure detection and restart detection.

  That is, after the elapse of the stabilization time, the detection means resumes detection in consideration of the time during which the sub-scan transport speed of the detection means or the photostimulable phosphor is stabilized. The accuracy of correction can be increased.

  An image input method according to the present invention is an image input method in which radiation image information is detected by a detector, and image information is input based on the detected radiation image, for correcting sensitivity of the detector. A step of detecting a radiation image when radiation is irradiated with a certain dose with the detector, and a sensitivity correction value of the detector is automatically set so that a signal value of the detected radiation image becomes a predetermined value. And detecting the radiation image information by the detector in order to secure a stable time of the factor accompanying the fluctuation when the sensitivity correction value is varied to obtain the sensitivity correction value. It is characterized by.

  According to this image input method, the sensitivity correction value is automatically obtained so that the signal value when a fixed dose is given becomes a predetermined value. The characteristic data of the means is not necessary and need not be input, and the sensitivity correction can be easily performed. Further, since calculation based on the characteristic data is not required, the accuracy of sensitivity correction is improved. Furthermore, by stopping the detection operation of the radiation image information when the sensitivity correction value is changed, it is possible to secure a stable time against the fluctuation factor accompanying the sensitivity correction, so that imaging for performing automatic calculation for sensitivity correction is performed. Even if the area is small, sufficient calculation can be performed. In this way, for example, it is possible to perform sufficient calculations for sensitivity correction even in cassettes with a small image-receiving surface, such as six-size cassettes that are relatively small in use size and special-purpose cassettes such as dental 15 × 30 cm cassettes. It becomes.

  In the image input method, an ideal value of the signal value when the constant dose is given is obtained in advance, and in the sensitivity correction step, the signal value when the sensitivity correction value is changed as an offset value is the ideal value. The offset value that is the same as the value can be obtained and used as the sensitivity correction value. Thus, the sensitivity correction value can be automatically obtained by comparing the signal value obtained by changing the offset value up and down with the ideal value and using the offset value as the sensitivity correction value.

  For example, a photomultiplier to which a voltage is supplied from a power source is used as the detector, the voltage of the power source is varied as an offset value, and the offset value that is the same as the ideal value is set as a correction voltage value. it can.

  In addition, it is preferable to determine a direction in which the voltage is changed when the correction voltage value is obtained based on responsiveness of the power supply when the voltage changes. For example, a high voltage power supply for a photomultiplier generally has a shorter rise time when the voltage is increased, and takes time by discharging a capacitor component when the voltage is decreased, so that the voltage is increased in the direction of increasing the voltage. By obtaining the correction voltage value, sensitivity correction can be performed more quickly, and the stabilization time can be minimized.

  Moreover, it is preferable to determine a stable time when the voltage fluctuates based on responsiveness of the power source when the voltage fluctuates. For example, a high-voltage power supply for a photomultiplier generally takes a longer time to stabilize when the voltage decreases, so by increasing the stabilization time when decreasing the voltage than when increasing the voltage, Sensitivity correction can be performed in the shortest time and with a stable voltage. It is preferable to set a standby time according to the characteristics of the high-voltage power supply and stop the detection operation for that time.

  Another image input method according to the present invention is an image input method in which radiographic image information is detected by a detector to obtain a signal value, and image information is input based on the detected radiographic image. Obtaining an ideal value of the signal value when a fixed dose is given, a plurality of offset values when the sensitivity correction value of the detector is changed, and the offset values obtained corresponding to the offset values Creating an approximate expression of the offset value and the signal value based on a signal value; obtaining an offset value corresponding to the ideal value from the approximate expression to be a sensitivity correction value of the detector; When the sensitivity correction value is varied, the detection of the radiation image information by the detector is stopped in order to ensure a stable time of the factor accompanying the variation.

According to this image input method, a sensitivity correction value can be obtained from an approximate expression and an ideal value from a plurality of offset values and signal values. Therefore, there is no need to input characteristic data of the detecting means and there is no need to input sensitivity Correction can be performed easily. Further, since calculation based on the characteristic data is not required, the accuracy of sensitivity correction is improved. Furthermore, by stopping the detection operation of the radiation image information when the sensitivity correction value is changed, it is possible to secure a stable time against the fluctuation factor accompanying the sensitivity correction, so that imaging for performing automatic calculation for sensitivity correction is performed. Even if the area is small, sufficient calculation can be performed. In this way, for example, even for cassettes with a small image-receiving surface, such as six-size cassettes that are relatively small in use size and special-purpose cassettes such as dental 15 × 30 cm cassettes, sufficient calculations for sensitivity correction are possible. It becomes. Note that the ideal value can be obtained by the following equation, for example.
Signal value (step) = αlog (X) + βlog (kando)
Where X: radiation dose (mR)
kando: value related to sensitivity (for example, QR value described later)
α, β: Constant

  Another image input method according to the present invention is an image input method in which radiographic image information is detected by a detector to obtain a signal value, and image information is input based on the detected radiographic image, A step of obtaining an ideal value of the signal value when a fixed dose is given, and a step of obtaining a plurality of signal values obtained corresponding to a plurality of offset values when the sensitivity correction value of the detector is changed And searching for a signal value corresponding to the ideal value from the plurality of signal values, and automatically discriminating an offset value at the signal value from the sensitivity correction value. When changing, the detection of the radiation image information by the detector is stopped in order to secure a stable time of the factor accompanying the change.

  According to this image input method, a signal value corresponding to an ideal value is searched from a plurality of signal values, and the offset value at that signal value is automatically determined as a sensitivity correction value. It is unnecessary and does not require input, and sensitivity correction can be easily performed. Further, since calculation based on the characteristic data is not required, the accuracy of sensitivity correction is improved. Furthermore, by stopping the detection operation of the radiation image information when the sensitivity correction value is changed, it is possible to secure a stable time against the fluctuation factor accompanying the sensitivity correction, so that imaging for performing automatic calculation for sensitivity correction is performed. Even if the area is small, sufficient calculation can be performed. In this way, for example, it is possible to perform sufficient calculations for sensitivity correction even in cassettes with a small image-receiving surface, such as six-size cassettes that are relatively small in use size and special-purpose cassettes such as dental 15 × 30 cm cassettes. It becomes.

  In the above-described image input method, when a photomultiplier supplied with a voltage from a power source is used as the detector, the offset value is the voltage value of the power source, and the sensitivity correction value is a correction voltage value of the power source. .

  In the image input device and the image input method described above, the signal value and the ideal value are the same not only when they match, but also when they are different but within a predetermined range. to decide.

  In the step of obtaining a plurality of the signal values obtained corresponding to the plurality of offset values of the other image input method described above, the plurality of signal values are determined from an offset value having a low voltage in consideration of responsiveness at the time of voltage fluctuation. It is preferable that a signal value corresponding to the ideal value is retrieved from the signal and an offset value at the time of the signal value is automatically determined from the sensitivity correction value.

  Further, when the sensitivity correction value is changed as the offset value in the above-described image input method and an offset value is obtained so that the signal value becomes the same as the ideal value, the fixed dose and the ideal By obtaining the sensitivity correction value after changing at least one of the values by a predetermined magnification, for example, when detecting a radiation image from the recording medium, the sensitivity correction value is obtained even if the recording medium has a sensitivity difference. Is possible.

  In each of the above image input methods, it is preferable that when the sensitivity correction value is changed, sub-scanning conveyance by relative movement between the detector and the photostimulable phosphor carrying the radiation image information is stopped. For example, when the photostimulable phosphor plate is transported for sub-scanning, the transport of the plate is stopped, or when the optical unit constituting the detection means is transported, the transport of the optical unit is stopped.

  Further, at least one of stopping the main scanning by the laser beam for exciting the photostimulable phosphor and turning off the laser beam may be performed. When stopping, the laser scanning for detection is stopped and the main scanning is stopped.

  Further, after the stable time has elapsed, detection by the detector may be resumed to obtain the next sensitivity correction value.

As described above, when a sufficient stabilization time is allowed after changing the voltage of the power supply, etc., the detection operation is restarted, and when the next correction value comparison operation is started, the stabilization time of the sub-scanning conveyance speed is required May take the stabilization time of the conveyance speed. When taking a stable transport time, return the photostimulable phosphor plate to the previously detected area to some extent, or return the optical unit of the detector. It is also possible to ensure detection and restart detection.
That is, after the stabilization time has elapsed, the detector restarts detection in consideration of the time during which the sub-scanning transport speed of the detector or the photostimulable phosphor that is transported in the sub-scanning state is stabilized. The accuracy of correction can be increased.

  According to the image input apparatus and image input method for detecting and inputting radiation image information of the present invention, sensitivity correction can be performed easily and accurately even when a small-size cassette / stimulable phosphor is used.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of a radiation image input apparatus according to an embodiment of the present invention. The radiographic image input device 50 of FIG. 1 is a CR type radiographic image input device that inputs radiographic image information by reading a radiographic image recorded on the photostimulable phosphor plate 4 as a recording medium. As shown, an input device 3 and a controller 18 are provided.

  The input device 3 shown in FIG. 1 accumulates a part of the radiation energy when irradiated with radiation, and then emits a luminescent light according to the accumulated radiation energy when irradiated with excitation light such as visible light or laser light. Using a stimulable phosphor, a sheet-like stimulable phosphor plate 4 formed by laminating a stimulable phosphor on a support is applied to a subject M such as a human body due to radiation irradiated from the radiation generator 30. The radiation image information once accumulated and recorded is scanned with a laser beam to sequentially emit light, and the photoelectric light is sequentially read by the photoelectric reading unit 20 to obtain an image signal. Then, the input device 3 irradiates the storage phosphor plate after reading the image signal with erasing light to release the radiation energy remaining on the plate, and prepares for the next imaging. The radiation generation apparatus 30 includes a radiation irradiation unit 31 that irradiates the subject M with radiation from a tube and a control unit 32 that controls the radiation irradiation unit 31.

  The input device 3 includes a stimulable phosphor plate 4 that records radiographic image information of a subject, a laser light source unit 6 that includes a laser diode that generates laser light as excitation light for the stimulable phosphor plate 4, and the like. A laser drive circuit 5 for driving the laser light source unit 6, an optical system 7 including a polygon mirror and a lens for main scanning the laser light from the laser light source unit 6 on the stimulable phosphor plate 4, and And a photoelectric reading unit 20 that collects the photostimulated luminescence excited by the excitation laser light and photoelectrically converts it to obtain an image signal.

  The photoelectric reading unit 20 condenses the photostimulated luminescence excited by the excitation laser light, and a photomultiplier (PMT) that functions as a detector by photoelectrically converting the light collected by the light collector 8. ) 10, a high voltage power supply 10 a that applies a voltage to the photomultiplier 10, a current-voltage conversion unit 11 that performs logarithmic voltage conversion on the current signal from the photomultiplier 10, and an analog signal from the current-voltage conversion unit 11 as A An A / D conversion unit 12 that performs / D conversion and a correction unit 13 that performs various corrections on the converted digital signal, and transmits a digital signal of the read radiation image data to the controller 18. The current / voltage conversion unit 11, the A / D conversion unit 12, and the correction unit 13 constitute a signal processing unit. The correction unit 13 has a memory for storing correction data and the like, and can correct density unevenness caused by the optical system and the light collection system by using the correction data as one of various corrections.

  The input device 3 further includes a halogen lamp 14 that emits erasing light and a driver 15 that drives the halogen lamp 14 in order to release radiation energy remaining on the photostimulable phosphor plate after the image signal is read. Have. The input device 3 also includes a control unit 17 that controls the laser drive circuit 5, the high-voltage power supply 10a, the current-voltage conversion unit 11, the A / D conversion unit 12, the correction unit 13, and the driver 15.

  Further, the laser light source unit 6, the optical system 7, the condenser 8, the photomultiplier 10, and the halogen lamp 14 of the input device 3 are integrally configured as a sub-scanning optical unit 9 as indicated by a broken line in FIG. The sub-scanning optical unit 9 has a sub-scanning direction (vertical direction in FIG. 1) perpendicular to a laser scanning (main scanning) direction (vertical direction in FIG. 1) by a sub-scanning motor and a ball screw mechanism (not shown). Move to. The sub-scanning optical unit 9 performs sub-scanning by moving in the sub-scanning direction during image reading, and the radiation image information remaining on the photostimulable phosphor plate 4 is emitted by the halogen lamp 14 during the backward movement. to erase. In this way, the radiation image recorded on the photostimulable phosphor plate 4 is automatically read to input information, and the afterimage after reading is erased, so that the next radiation imaging can be performed.

  The controller 18 includes a personal computer main body 25, a keyboard 26, and a monitor display unit 27. The digital signal of radiation image data received from the input device 3 is temporarily stored in a memory, image-processed, and the keyboard 26. The display on the monitor display unit 27 and image processing are controlled in accordance with the operation input from, and the image-processed radiation image data is output to the outside.

  Note that the photostimulable phosphor plate 4 may be configured to obtain radiation image information of the subject M by being irradiated with radiation from the radiation generator 30 in a state of being accommodated in a cassette having a size corresponding to the size. The radiation image can be read from the photostimulable phosphor plate 4 in the same image input apparatus as that shown in FIG.

  In the CR system such as the image input device 50 in FIG. 1, the sensitivity correction is performed because the sensitivity of the PMT and the sensitivity of the stimulable phosphor plate (the amount of the stimulating light) are not necessarily the same offset with respect to the irradiation dose. It is necessary to make it work. As the sensitivity correction operation, by changing the voltage applied to the PMT, the current value output from the bleeder circuit of the PMT is set to a certain signal value when the same dose and the same plate are used. .

  As a method for obtaining this applied voltage, a theoretical signal value for the irradiation dose is determined, the plate exposed to the irradiation dose actually set to the theoretical value is read, and the applied voltage is changed to obtain the same signal value as the theoretical value. Find the voltage value. As a method for obtaining this, in the method of Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-77709), the applied voltage is changed without breaking the normal plate reading operation, and the voltage is changed while taking sufficient time when the voltage is changed. There is a way to find the value.

  Next, sensitivity adjustment of the photomultiplier 10 in the input device 3 of FIG. 1 will be described. FIG. 2 is a flowchart showing steps for obtaining a voltage setting value in the high-voltage power supply 10a for sensitivity correction of the photomultiplier 10 of FIG.

  In the CR system, in order to efficiently use the limited detection capability (dynamic range) of a detector composed of a photomultiplier, signal values for a certain radiation dose are allocated, and the allocation method has several patterns. In some cases, each offset value is set with a pattern such as a large radiation dose, a normal radiation dose, or a low radiation dose. In this embodiment, the offset value is obtained in the following steps.

  That is, in the CR-type radiation image input device as shown in FIG. 1, the stimulable phosphor plate 4 having a predetermined size is irradiated with a certain dose (eg, AmR) (S01). The ideal value of the signal value when radiation is irradiated with this AmR dose is determined as “B” (S02). The ideal signal value can be obtained from a predetermined algorithm as described later, for example.

  Next, when the light emitted from the photostimulable phosphor plate 4 is detected by the photomultiplier 10, the voltage applied to the photomultiplier 10 from the high voltage power source 10a is varied up and down as an offset value, In the voltage value, the signal value C output from the correction unit 13 of the signal processing unit in FIG. 1 is read (S03).

  Then, the signal value C is compared with the ideal signal value B, the voltage value is adjusted by changing the voltage of the high-voltage power supply 10a so that the signal value C becomes the ideal signal value B (S04), and the signal value C is ideal. The voltage that is the same as the signal value B is set as a correction voltage value in the high-voltage power supply 10a (S05).

  As described above, the sensitivity of the photomultiplier 10 can be adjusted by automatically obtaining an appropriate voltage to be applied to the photomultiplier 10 and setting this voltage value in the high-voltage power supply 10a. The sensitivity correction of the photomultiplier 10 can be performed, for example, at the time of shipment so that the same model has the same sensitivity in the radiation image input apparatus as shown in FIG. 1, and is performed at the time of maintenance when the photomultiplier or the like deteriorates. be able to. Each step as described above can be controlled and executed by the control unit 17 of FIG.

  According to the sensitivity correction in the radiographic image input apparatus of FIG. 1 as described above, the sensitivity correction can be performed by one radiation irradiation for sensitivity correction, and it is not necessary to input characteristic graph information of a detector such as PMT, Since sensitivity correction can be performed with the radiation dose value and the signal value after imaging, sensitivity correction can be easily performed. In addition, since there is no extra calculation, the accuracy of sensitivity correction is improved.

  Next, a description will be given of an appropriate voltage variation method in consideration of responsiveness at the time of voltage variation of the high-voltage power supply with reference to FIG. FIG. 3 is a diagram illustrating an example of an input voltage waveform (a) of a control signal applied to the high voltage power source 10a of FIG. 1 and an example of an output voltage waveform (b) from the high voltage power source 10a.

  When the input voltage of the control signal in FIG. 3A is input and turned on, the high voltage power supply 10a in FIG. 1 rises as shown in FIG. 3B and reaches 90% of the target output voltage V. The rise time tr tends to be shorter than the fall time tf in which the output voltage decreases to 10% of the target output voltage V as shown in FIG.

  Therefore, considering the stabilization time of the high-voltage power supply 10a, searching for the corresponding signal value by changing the voltage from the low direction to the high direction results in a shorter total processing time. The effect of fading can be reduced, and cost reduction effects such as man-hour reduction by shortening the processing time can be expected.

  Here, a mechanism is considered in which a comparison operation is sequentially performed with a theoretical value while actually reading a radiation image. For example, when the pixel size is 200 μm pitch, for example, when the size is half cut (432 mm × 356 mm), the pixel size is 2160 × 1780 pixels. When 5 lines are required for averaging image data, the conveying direction of the photostimulable phosphor plate 4 (or the sub-scanning optical unit such as the laser light source unit 6 and the optical system 7) is called the sub-scanning direction, and the laser light source unit When the scanning direction of the excitation laser beam by 6 is the main scanning, 2160 ÷ 5 = 432 comparison operations can be performed from 2160 lines in the entire sub-scanning direction.

  Actually, when obtaining the acquisition signal C for comparison with the ideal signal value B by varying the voltage of the high-voltage power supply 10a, the stabilization time of the high-voltage power supply considering the rise time tr and the fall time tf. Is required.

  For example, if there is a high voltage power supply module that can output 0 to 1000 V as the output range of the high voltage power supply 10a, has a rise time tr of 100 ms, and a fall time tf of 400 ms, for example, one line scanning time of an image is 10 ms. In some cases, it is necessary to ensure the stable time of the high-voltage power supply by prohibiting the irradiation for 10 lines at the rising edge and 40 lines at the falling edge. In that case, in the case of rising, the average calculation is 5 lines and the high-voltage power supply stabilization time at the time of rising is 10 lines, and the comparison operation is 2160 ÷ 15 = 144 times. In the case of falling, 2160 ÷ 45 = Only 48 comparison operations can be performed.

  Considering how much the number of comparison calculations needs to be made, assuming that the setting resolution of the high-voltage power supply 10a is 12 bits, for example, if the high-voltage power supply is shaken in the full range from the minimum value to the maximum value, 4096 comparison operations will be performed. It needs to be possible. However, in practice, if the voltage is not set in the signal range near the minimum value or the maximum value where the voltage saturates, it is sufficient if the comparison operation can be performed about 2000 times, which is half of the maximum value.

  Further, for example, as in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-77709), the correction range is divided into large cut-out areas, and the location of the large cut-out area is first examined, and the details in that area are checked. By using the method of performing the comparison operation, it is possible to end the comparison operation by about 100 times. For example, the upper 7 bits (128) are divided into large regions, comparison operations are performed in the regions, and when the regions are determined, the remaining detailed 5 bits (32) are compared and the theoretical values and actual measurements are performed. Adjust the values. Since the upper and lower regions cannot actually be used as the set value of the high voltage output, the comparison operation itself may be performed within the range where the region having the minimum value and the maximum value is excluded. For this reason, as described above, the comparison operation can be completed in about 100 times.

  Here, in the above description, a half-cut (432 mm × 356 mm / 14 inch × 17 inch) size is taken as an example, but actually there are even smaller cassettes, depending on how they are used in the market. In some cases, only small-sized cassettes are used. For example, as a small cassette, six sizes (8 inches × 10 inches) and a dental 15 cm × 30 cm cassette cannot perform 100 comparison operations as described above.

  Even when the cassette size is small, when the voltage value of the high-voltage power supply 10a is fluctuated to ensure the stable time, the reading operation by the photomultiplier 10 is stopped, so that the idle reading time at the rising time tr and the falling time tf is stopped. Therefore, it is possible to perform comparison operation 100 times or more.

  The reading operation can be stopped by stopping the sub-scanning conveyance of the sub-scanning optical unit 9 by stopping the sub-scanning motor in the image input apparatus 50 of FIG.

  Further, when the sub-scanning optical unit 9 stops the sub-scanning conveyance, the laser light source unit 6 of the sub-scanning optical unit 9 may be turned off. Further, the main scanning operation by the laser light from the laser light source unit 6 may be stopped. The main scanning operation includes, for example, a polygon motor driving using a polygon mirror, a galvanometer, and the like, and these operations are stopped. After the above-described stabilization time has elapsed, the sub-scan transport / main scan operation is restarted. The off state of the laser light source unit 6 includes not only blocking the current to the laser diode, but also includes a case where a minute current flows and a substantially non-light emitting state.

  As described above, even if the voltage of the high-voltage power supply 10a is changed from a high direction to a low direction and the voltage stabilization time becomes long, the reading operation is stopped to ensure a sufficient number of comparison operations. Can do.

  Next, a specific example of obtaining an appropriate correction voltage value to be set in the photomultiplier 10 by changing the voltage value of the high-voltage power supply 10a will be described with reference to FIG. FIG. 4 is a plan view showing a region where the stimulable phosphor plate 4 of FIG. 1 is irradiated with radiation during sensitivity correction.

  First, the stimulable phosphor plate 4 is irradiated with radiation for sensitivity correction. Here, several pixels are cut out in the left and right regions 4b of the photostimulable phosphor plate 4 and, if necessary, in the upper and lower regions 4a, and the irradiation region 4c irradiated with the X-rays therein is read. Further, regarding the X-ray irradiation dose at this time, dose measurement is separately performed at the same tube voltage, the same dose (current, time), and the same distance as when the stimulable phosphor plate 4 is irradiated. The actual imaging distance for sensitivity correction and the X-ray dose measurement need to be performed not only at the same dose but also at the same distance.

  Then, after irradiation for sensitivity correction to the photostimulable phosphor plate 4, the laser light from the laser light source unit 6 performs main scanning in the lateral direction of the irradiation region 4c in FIG. 4, and the sub scanning optical unit 9 performs sub scanning. By being sub-scanned and transported in the scanning direction (for example, upward in FIG. 2), the photostimulable light emitted from the photostimulable phosphor plate 4 is detected by the photomultiplier 10 via the light collector 8. Then, the image data is read as a signal value (actually measured step value) from the signal processing unit.

  When performing sensitivity correction, the sensitivity setting value proportional to the voltage applied to the photomultiplier 10 is defined as QR, and the voltage value of the high-voltage power supply 10a is varied for each of QR = 50, 250, and 500. At this time, for example, a predetermined radiation dose such as 10.00 mR is input. For example, in the case of a CR system as shown in FIG. 1, the radiation dose range is a range in which the signal does not saturate up and down in consideration of system errors (for example, the bottom is about 8 mR from the top to the top Can be freely selected within a range of about 20 mR that does not saturate.

  Moreover, the ideal signal value in step S02 of FIG. 2 is obtained as follows. That is, an ideal signal value (step) is obtained from the QR value to be obtained and the value of the incident dose X (mR), for example, by the following equation.

step = 444.72 × ln (X) + 1024 × log (QR) −821.26
However, the precision shall be ln (X): third decimal place, log (QR): fourth decimal place.
The step value is 12-bit data. This equation can be stored, for example, by the control unit 17 in FIG. 1, and the QR value and the value of the incident dose X can be input from the keyboard 26 of the controller 18 in FIG.

  The ideal step value is calculated according to the following algorithm for the voltage setting method of the high-voltage power supply and the actually measured step value is measured.

  The voltage setting in the high-voltage power supply 10a is specifically performed as follows. For example, in a high voltage power source capable of outputting 0 to 1000 V, the control voltage range of the high voltage output is 0 to 6 V, for example, the high voltage control set value is 12 bits (the 12 bit set value is 0 to 6 V high voltage control voltage, The control voltage of 6V and the output voltage of 0 to 1000V are proportional to each other.), And the rising characteristic is good (for example, 100 ms), and the falling output decreases relatively slowly (for example, 400 ms) The present inventor has proposed the following method in Japanese Patent Application Laid-Open No. 2004-77709.

  In other words, at the input voltage (maximum fluctuation width 6V), the maximum reduction width at one time is within 0.2V (12bit set value is 135 or less, within 8bit), and the maximum increase width of the input voltage is also within 0.2V. (Within 8 bits). When starting up the voltage after changing the voltage setting value for the high-voltage power supply 10a, the signal value is read by the photomultiplier 10 after taking a stabilization time of 100 ms (for example, 20 lines if the scanning time of one line is 5 ms). Start. When the voltage falls, a stabilization time of 400 ms (80 lines) is taken. When the voltage is varied in a narrow range of 7 bits or less, there is no difference in the rising and falling characteristics, and it can be handled by taking a stabilization time of 100 ms (20 lines).

  As described above, 20 lines or 80 lines are read as a stable time when the voltage value of the high-voltage power supply 10a is changed while performing a constant reading operation in the sub-scanning direction. However, when such an idle reading operation is performed, a sufficiently small number of comparison operations cannot be secured with a small-size cassette, for example, a six-size cassette or a 15 × 30 cm cassette.

  Therefore, as shown in the flowchart of FIG. 5, the stable time of the high-voltage power supply 10a is ensured. That is, as shown in FIG. 5, when the set voltage of the high-voltage power supply 10a is changed (S11), the reading operation is performed in order to ensure a stable rising time, for example, 100 ms, and a stable falling time, for example, 400 ms. Stop. As such control, after reading the image data for five lines, the irradiation of the laser light from the laser light source unit 6 is stopped (S12), and the sub-scanning conveyance of the sub-scanning optical unit 9 is stopped (S13).

  Then, it waits until the stable time of the high-voltage power supply 10a elapses, and when the stable time is sufficiently secured (S14), the laser beam irradiation is restarted (S15), and the sub-scanning conveyance of the sub-scanning optical unit 9 is restarted (S15). S16) The image data is read.

  As described above, by controlling the sub-scanning conveyance stop (S13) of the sub-scanning optical unit 9, conventionally, the sub-scanning conveyance is advanced by the voltage stabilization time, and the image data is wasted. When it is difficult to find the value, or when the photostimulable phosphor plate size is small, the reading operation of one photostimulable phosphor plate is completed before the same reading as the theoretical value is found. Thus, the image data on the photostimulable phosphor plate can be fully utilized.

  In addition, by stopping the sub-scanning conveyance, the comparison between the theoretical value and the reading value has been simplified so far by simplifying the comparison process only by determining whether it is up, down, or equal. It is also possible to set the set voltage value near the theoretical value instead of simply incrementing the value of the applied voltage at the time of the next comparison work by calculating how far it is from the theoretical value .

  Here, a mechanism in consideration of the time during which the conveyance speed of the sub-scanning optical unit 9 is stabilized may be adopted. By making the conveyance speed of the sub-scanning optical unit 9 constant, the reading pixel pitch in the sub-scanning direction becomes constant, and the pre-exposure effect (because the laser light has a Gaussian distribution instead of a rectangle, the amount of the sub-scanning optical unit 9 is small in advance but It is possible to suppress the influence of a phenomenon in which the scanning line is partially exposed) and to increase the accuracy of sensitivity correction.

  For example, when the arrival distance from the stop to a constant speed is required 5 mm in the sub-scanning direction, image data for five lines is read, and the sub-scanning distance is returned by 5 mm when the laser beam is stopped and the sub-scanning conveyance is stopped. This makes it possible to obtain an acceleration distance of 5 mm when reading the next line. After returning to the 5 mm sub-scanning distance and waiting and securing a stable time due to the transition of the high-voltage power supply 10a, the sub-scanning transport operation is resumed. When 5 mm has passed, reading is resumed for 5 lines. Since the acceleration time and the acceleration distance depend on the transport performance of the sub-scanning of the apparatus, it is sufficient to take a distance that can move at a constant speed at a speed sufficiently set by the transport performance.

  Here, as position control in the sub-scanning direction, assuming that there is a signal from an encoder, for example, the resolution of the encoder is sufficiently larger than the sampling pitch. For example, the sub-scanning position information is encoded with a resolution of 10 μm per pulse of the encoder signal. In the system controlled by using the sub-scanning optical unit 9, the sub-scanning optical unit 9 is returned to the area already read in the sub-scanning direction by 5000 μm (500 pulses). After that, when the stable time of the high-voltage power supply 10a is sufficiently secured, the sub-scanning motor is accelerated in the sub-scanning direction for 500 pulses to a constant speed, and after 500 pulses, 5 lines for averaging the image data. Image data (for example, 200 μm × 5 lines = 1000 μm (100 pulses)) is taken in.

  At this time, since the above-described pre-exposure effect may be affected not only by the case where the conveyance speed is not constant but also by a slight misalignment of the overlay, the sub-scanning direction 1 is always used. The image data may be read after the line has been left open.

  In the case where an idle reading of one line in the sub-scanning direction is performed after returning 500 pulses as described above, the image data may be read after 520 pulses by accelerating by 520 pulses and operating at a constant speed.

  Alternatively, the acceleration time and acceleration speed at the same speed are considered to be constant, and the value may be calculated by the following method by the method of collecting the image data immediately after the start of conveyance without performing the process of inserting the acceleration time. . This is because a ratio (S1 / S2) between the signal value S1 when data is acquired in advance at a constant speed and the signal value S2 collected at the acceleration time is calculated in advance, and the value of the ratio is calculated for each subsequent comparison operation. In this method, the image data Sx collected at the acceleration time is multiplied and used as calculation data. In the initial initial operation of the calibration work, the image data including the acceleration time at the beginning of reading and the image data at a sufficiently constant speed are read, the ratio is obtained, and used for the subsequent comparison of calibration. It's okay.

  As described above, during the calibration operation in the image input apparatus 50 of FIG. 1, the voltage applied from the high-voltage power supply 10a to the PMT 10 is changed to perform the comparison operation between the theoretical value and the actually measured (read) value. In the cassette / stimulable phosphor plate having a relatively small size (six-cut cassette or dental 15 × 30 cm cassette) by stopping the scanning operation of the scanning optical unit 9 and the laser beam irradiation and stopping the reading operation. However, it is possible to ensure a stable time of the power supply voltage at the time of transition of the applied voltage, and to sufficiently perform a comparison operation between the theoretical value and the actually measured (read) value within a small size. As a result, even with a relatively small cassette / stimulable phosphor plate, sensitivity calibration can be performed without any problem by one exposure.

  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, the reading operation of the present embodiment is stopped by stopping the sub-scanning conveyance of the sub-scanning optical unit 9 in the image input device 50 of FIG. 1, but the stimulable phosphor plate is sub-scanned and conveyed. In the case of the type of image input device, the sub-scanning conveyance of the photostimulable phosphor plate is stopped.

  In FIG. 5, steps S11 to S13 are not limited to the order shown in FIG. 5. For example, step S11 for changing the set voltage of the high-voltage power supply 10a may be executed after stopping the sub-scanning conveyance. Of course, the order of execution of the laser beam irradiation stop in step S12 and the sub-scanning conveyance stop in step S13 may be reversed.

It is the schematic of the radiographic image input device by this Embodiment. It is a flowchart which shows the step which calculates | requires the voltage setting value in the high voltage power supply 10a for the sensitivity correction of the photomultiplier 10 of FIG. It is a figure which shows the example of the input voltage waveform (a) of the control signal applied to the high voltage power supply 10a of FIG. 1, and the example of the output voltage waveform (b) from the high voltage power supply 10a. It is a top view which shows the area | region which irradiates a radiation to the photostimulable phosphor plate 4 of FIG. 1 at the time of the above-mentioned sensitivity correction. 3 is a flowchart for explaining steps for ensuring a stable time of the high-voltage power supply 10a when the set voltage is changed during sensitivity correction of the radiation image input apparatus of FIG.

Explanation of symbols

4 Stimulable Phosphor Plate 6 Laser Light Source 7 Optical System 8 Condenser 9 Sub-Scanning Optical Unit 10 Photomultiplier, PMT (Detection Means)
10a High-voltage power supply 20 Photoelectric reader 50 Radiation image input device tf Rise time tr Fall time

Claims (28)

An image input device comprising detection means for detecting radiation image information, wherein image information is input based on the detected radiation image,
A sensitivity correction unit that automatically obtains a sensitivity correction value of the detection unit such that the signal value of the radiation image detected by the detection unit when a certain dose is given becomes a predetermined value;
A detection stop means for stopping detection of radiation image information by the detection means in order to secure a stable time of a factor accompanying the fluctuation when the sensitivity correction value is changed in order to obtain the sensitivity correction value. An image input device.   The apparatus further includes a storage unit that stores an ideal value of the signal value when the constant dose is given, and the signal value when the sensitivity correction unit changes the sensitivity correction value as an offset value is the ideal value. The image input apparatus according to claim 1, wherein the offset value that is equal to the value is obtained and used as the sensitivity correction value. The detection means includes a photomultiplier having a photoelectric conversion function, and a power source for supplying a voltage to the photomultiplier,
The image input device according to claim 1, wherein the voltage value of the power source is varied as an offset value, and the offset value that makes the signal value the same as the ideal value is used as a correction voltage value.   The image input device according to claim 3, wherein the correction voltage value is obtained in a direction in which the voltage of the power supply is increased. A photomultiplier that detects light emitted from a stimulable phosphor that is supplied with a voltage from a power source and carries the radiation image information as the detection means, the offset value is a voltage value of the power source, and the sensitivity correction Find the correction voltage value as the value,
The image input device according to claim 2, wherein the correction voltage value is obtained after changing at least one of the constant dose and the ideal value at a predetermined magnification based on a sensitivity difference between the photostimulable phosphors. As the detection means, the photostimulable phosphor is obtained by relative movement between a stimulable phosphor that is supplied with a voltage from a power source and carries the radiation image information, and a scanning means that irradiates the stimulable phosphor with excitation light. Using a photomultiplier that detects photostimulated light emitted from
The offset value is a voltage value of the power source, and a correction voltage value is obtained as the sensitivity correction value.
The image input apparatus according to claim 2, wherein the correction voltage value is obtained by correcting a difference in luminance signal value difference due to a difference in pitch of the relative movement. An image input device comprising detection means for detecting radiographic image information and obtaining a signal value, and inputting image information based on the detected radiographic image,
Storage means for storing an ideal value of the signal value when a certain dose is given;
Approximation of the offset value and the signal value created on the basis of a plurality of offset values when the sensitivity correction value of the detecting means is changed and the signal value obtained corresponding to each offset value A sensitivity correction unit that obtains an offset value corresponding to the ideal value from the equation and sets it as a sensitivity correction value of the detection unit;
An image input apparatus comprising: a detection stop unit that stops detection of radiation image information by the detection unit in order to ensure a stable time of a factor accompanying the change when the sensitivity correction value is changed. . An image input device comprising detection means for detecting radiographic image information and obtaining a signal value, and inputting image information based on the detected radiographic image,
Storage means for storing an ideal value of the signal value when a certain dose is given;
The signal value corresponding to the ideal value is searched from the plurality of signal values obtained corresponding to the plurality of offset values when the sensitivity correction value of the detecting means is changed, and the offset value at the time of the signal value Sensitivity correction means for automatically discriminating from the sensitivity correction value;
An image input apparatus comprising: a detection stop unit that stops detection of radiation image information by the detection unit in order to ensure a stable time of a factor accompanying the change when the sensitivity correction value is changed. . The detection means has a photomultiplier having a photoelectric conversion function, and a power supply for supplying a voltage to the photomultiplier,
The image input device according to claim 7, wherein the offset value is a voltage value of the power source, and the sensitivity correction value is a correction voltage value of the power source.   The image input according to any one of claims 1 to 9, wherein the detection stop unit stops sub-scanning conveyance by relative movement between the detection unit and the photostimulable phosphor carrying the radiation image information. apparatus.   The image according to claim 10, wherein the detection stopping unit performs at least one of stopping main scanning by a laser beam for exciting the photostimulable phosphor and turning off the laser beam. Input device.   The image input device according to claim 1, wherein the detection unit resumes detection after the stabilization time has elapsed, and the sensitivity correction unit obtains a next sensitivity correction value.   The detection means restarts the detection in consideration of the time during which the sub-scan transport speed of the photostimulable phosphor or the detection means transported by the sub-scan is stabilized after the stabilization time has elapsed. 12. The image input device according to 12. An image input method in which radiation image information is detected by a detector, and image information is input based on the detected radiation image,
The step of detecting a radiation image when the radiation is irradiated with a certain dose for sensitivity correction of the detector with the detector, and the signal value of the detected radiation image becomes a predetermined value. Automatically determining a sensitivity correction value of the detector,
When the sensitivity correction value is varied in order to obtain the sensitivity correction value, the detection of the radiation image information by the detector is stopped in order to ensure a stable time of the factor accompanying the variation. Obtain in advance the ideal value of the signal value when giving the constant dose,
The image according to claim 14, wherein in the sensitivity correction step, the offset value is obtained so that the signal value when the sensitivity correction value is changed as an offset value is the same as the ideal value, and is used as the sensitivity correction value. input method.   The photomultiplier to which a voltage is supplied from a power source as the detector, the voltage of the power source is varied as an offset value, and the offset value that is the same as the ideal value is used as a correction voltage value. 15. The image input method according to 15.   The image input method according to claim 16, wherein a direction in which the voltage is varied when determining the correction voltage value is determined based on responsiveness of the power supply when the voltage varies.   The image input method according to claim 16, wherein the correction voltage value is obtained in a direction in which the voltage of the power supply is increased.   The image input method according to claim 16 or 17, wherein a stable time at the time of fluctuation of the voltage is determined based on responsiveness at the time of voltage fluctuation of the power source. An image input method in which radiation image information is detected by a detector to obtain a signal value, and image information is input based on the detected radiation image,
Obtaining an ideal value of the signal value when a certain dose is given, a plurality of offset values when the sensitivity correction value of the detector is changed, and obtained corresponding to each offset value Creating an approximate expression of the offset value and the signal value based on the signal value, obtaining an offset value corresponding to the ideal value from the approximate expression, and setting it as a sensitivity correction value of the detector; Including,
When changing the sensitivity correction value, the detection of radiation image information by the detector is stopped in order to ensure a stable time of a factor accompanying the change. An image input method in which radiation image information is detected by a detector to obtain a signal value, and image information is input based on the detected radiation image,
Obtaining a plurality of signal values obtained corresponding to a plurality of offset values when the sensitivity correction value of the detector is changed, and obtaining an ideal value of the signal value when a certain dose is given; Searching for a signal value corresponding to the ideal value from the plurality of signal values, and automatically discriminating an offset value at that signal value from the sensitivity correction value,
When changing the sensitivity correction value, the detection of radiation image information by the detector is stopped in order to ensure a stable time of a factor accompanying the change.   The photomultiplier supplied with a voltage from a power source as the detector, the offset value is a voltage value of the power source, and the sensitivity correction value is a correction voltage value of the power source. Image input method.   In the step of obtaining a plurality of the signal values obtained corresponding to the plurality of offset values, a signal corresponding to the ideal value from the plurality of signal values is determined from an offset value having a low voltage in consideration of responsiveness at the time of voltage fluctuation. 23. The image input method according to claim 21, wherein a value is searched and an offset value at the time of the signal value is automatically determined from the sensitivity correction value.   The image input method according to claim 23, wherein the sensitivity correction value is obtained after changing at least one of the constant dose and the ideal value at a predetermined magnification.   25. The sub-scanning conveyance by the relative movement between the detector and the photostimulable phosphor carrying the radiation image information is stopped when the sensitivity correction value is changed. The image input method described.   26. The image input method according to claim 25, wherein at least one of stopping main scanning with a laser beam for exciting the photostimulable phosphor and turning off the laser beam is performed.   The image input method according to any one of claims 14 to 26, wherein the detection by the detector is resumed after the stabilization time has elapsed to obtain a next sensitivity correction value.   27. The detector restarts detection in consideration of the time during which the sub-scan transport speed of the detector or the photostimulable phosphor is stabilized after the stabilization time has elapsed. 27. The image input method according to 27.

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