JPH11112730A - Method and device for adjusting read sensitivity of radiation picture information reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct read sensitivity to make it easy for a user to understand at a method and device for adjusting the read sensitivity of a radiation picture information reader. SOLUTION: Picture information is read from a sheet 1 recording a solid picture by a prescribed recording condition to obtain a sensitivity characteristic value S0 expressing the read sensitivity of a read part and to obtain an expected characteristic value S1 expressing the read sensitivity of the read part which should be obtained on the prescribed recording condition by a sensitivity characteristic setting means A voltage detection means 52 detects the high voltage V0 of a photomultiplier 24 and arithmetic of V1=V0×10<-> PMTK×(<log> <s> 1 -log s0 ) (PMTK is a parameter showing a relation between the applied high voltage of the photomultiplier 24 and gain) to obtain a high voltage V1 to apply this value V1 to the photocell 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for adjusting the reading sensitivity of a radiation image information reading apparatus.

[0002]

2. Description of the Related Art A stimulable phosphor sheet (hereinafter, simply referred to as a "sheet") on which radiation image information is accumulated and recorded is irradiated with excitation light such as a laser beam, and the radiation image information accumulated and recorded on the sheet is irradiated on the sheet. There has been known a radiation image information reading apparatus that detects stimulating light that emits stimulating light in response thereto and reads out radiation image information (Japanese Patent Application Laid-Open No. 62-18536, etc.).

In such a radiation image information reading apparatus, for example, a laser beam is scanned over the entire surface of a sheet by a light beam scanning means, and stimulated emission light emitted from the sheet is transmitted through a light guide to a photomultiplier (photomultiplier). )
And the like, converts the light into an electric signal (image signal), performs predetermined image signal processing on the obtained image signal by the signal processing means, and uses the processed image signal to perform photography. By outputting the radiation image information as a visible image on a recording material such as a photosensitive material or a display device such as a CRT, it is possible to obtain a radiation image which is not affected by the fluctuation of the radiation exposure amount. The signal processing unit converts, for example, an image signal obtained by the photoelectric conversion unit into a logarithmic amplifier (log amplifier).
Logarithmic conversion, and converts the logarithmized image signal into analog /
After being converted into digital image data (pixel values) by a digital converter (A / D converter) and subjecting the digital image data to desired image processing such as frequency processing and gradation processing, a TV such as an NTSC system is used. Or convert it to an image signal for use.

[0004]

Since the photostimulated light emitted from the sheet has a wide dynamic range of light quantity, a photomultiplier is generally used as a photoelectric conversion means for detecting the photostimulated light. In the photomultiplier, the reading gain (the magnitude of the output signal with respect to the amount of incident light) is determined by the applied high voltage, and by adjusting this high voltage, light of a small amount or light of a considerably large amount is desired. It is possible to obtain an output signal having the following value. Therefore, in the radiation image information reading device, the reading gain of the photomultiplier is adjusted by adjusting the high voltage applied to the photomultiplier to a desired high voltage value so that reading at a desired signal level is performed. Thereby, the reading sensitivity of the entire reading apparatus is adjusted.

Here, the reading sensitivity of the photomultiplier changes with time, so that it is necessary to periodically adjust the reading sensitivity. Also, when it is desired to match the reading sensitivity of a plurality of radiation image information reading apparatuses to the reading sensitivity of one reference radiation image information reading apparatus, the work of adjusting the sensitivity of each photomultiplier of the remaining apparatuses is required. Need to be done.

[0006] Such read sensitivity adjustment is performed as follows. That is, first, a predetermined amount of radiation serving as a reference is applied to the sheet to store a predetermined amount of energy substantially uniformly (hereinafter, this is referred to as “solid exposure”).
The irradiated sheet is scanned with a predetermined amount of laser light, and the photostimulated light emitted thereby is read by a photomultiplier. Next, a predetermined conversion is performed by obtaining a QL value which is an average pixel value of all pixel values read by the photomultiplier. Further, sensitivity correction is performed by adding correction data to the converted QL value, and based on the data subjected to the sensitivity correction, a deviation amount between the desired reading sensitivity and the actual reading sensitivity (sensitivity deviation amount). Ask for. The sensitivity shift amount thus obtained is converted into a value of a high voltage of the photomultiplier, and the value of the high voltage is applied to the photomultiplier.

However, the above-described read sensitivity adjusting method requires processing such as conversion and addition of correction data, and values for conversion and correction have values directly related to read sensitivity. However, it was very difficult for the user to understand.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a reading sensitivity adjustment method and apparatus for a radiation image information reading apparatus which is easy for a user to understand.

[0009]

According to the present invention, there is provided a method and apparatus for adjusting a reading sensitivity of a radiation image information reading apparatus, which comprises an index value S representing a reading sensitivity peculiar to the radiation image information reading apparatus.
The reading sensitivity is adjusted using the value. That is, the read sensitivity adjusting method of the radiation image information reading apparatus according to the present invention includes the reading sensitivity adjustment of the radiation image information reading apparatus that reads the radiation image information from a recording medium on which the radiation image information is recorded by a reading unit including a photoelectric conversion unit. The method, by reading the image information on the recording medium on which the radiation solid image information is recorded under predetermined recording conditions by the photoelectric conversion unit, to obtain a sensitivity index value representing the read sensitivity of the reading unit, The reading sensitivity of the reading unit is corrected based on an expected index value indicating the reading sensitivity of the reading unit to be obtained under predetermined recording conditions and the sensitivity index value.

Here, the "recording medium on which solid image information is recorded" is a recording medium on which uniform image information is recorded at a predetermined image level. For example, a predetermined amount of radiation is applied to the recording medium. It is preferable that a predetermined amount of energy is stored substantially uniformly (hereinafter, this is referred to as “solid exposure”).

The "reading sensitivity" is an index representing the relationship between the input and output of the entire image information reading apparatus.

In the reading sensitivity adjusting method according to the present invention, the reading sensitivity is preferably corrected by correcting a high voltage value applied to the photoelectric conversion means. S0, the expected index value is S1, the high-voltage voltage value of the photoelectric conversion means when obtaining the sensitivity index value S0 is V0, the correction value of the high-voltage voltage value to be applied to the photoelectric conversion means is V1, When a parameter representing the relationship between the high voltage applied to the photoelectric conversion means and the read gain of the photoelectric conversion means is PMTK, an operation of V1 = V0 × 10 ^−PMTK × ^{(log S1−log S0)} is performed. More preferably, the high voltage value applied to the photoelectric conversion means is corrected.

Further, the reading sensitivity adjusting device according to the present invention is
A reading sensitivity adjustment device of a radiation image information reading device that reads the radiation image information from a recording medium on which the radiation image information is recorded by a reading unit including a photoelectric conversion unit, wherein the radiation solid image information is obtained under predetermined recording conditions. An index value calculating unit that reads the recorded image information on the recording medium by the photoelectric conversion unit and obtains a sensitivity index value representing a reading sensitivity of the reading unit; and the reading to be obtained under the predetermined recording condition. A reading sensitivity correction unit that corrects the reading sensitivity of the reading unit based on the expected index value indicating the reading sensitivity of the unit and the sensitivity index value.

Further, in the read sensitivity adjusting device according to the present invention, the read sensitivity correcting means may be a means for correcting the read sensitivity by correcting a high voltage value applied to the photoelectric conversion means. Preferably, in this case,
The sensitivity index value is S0, the expected index value is S1, the high-voltage voltage value of the photoelectric conversion unit when the sensitivity index value S0 is obtained is V0,
The correction value of the high voltage value to be applied to the photoelectric conversion means is
V1 = ^{Calculation of} V1 = V0 × 10 ^−PMTK × ^{(log S1−log S0)} , where PMTK is a parameter representing the relationship between the high voltage applied to the photoelectric conversion unit and the read gain of the photoelectric conversion unit. And a means for correcting the high voltage value applied to the photoelectric conversion means.

[0015]

According to the method and apparatus for adjusting the reading sensitivity of a radiation image information reading apparatus according to the present invention, an S value which is an index value representing the reading sensitivity peculiar to the radiation image information reading apparatus is used, and a predetermined recording condition is obtained. In order to adjust the reading sensitivity from the relationship between the sensitivity index value obtained by recording a solid image and reading it, and the expected index value expected under recording conditions when the recording and reading were performed, The reading sensitivity can be adjusted by directly controlling the index value indicating the reading sensitivity, and the adjustment is very easy for the user to understand.

Further, since the high voltage applied to the photomultiplier can be controlled on the basis of the relationship between the S values, extremely simple adjustment can be performed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of a sensitivity adjustment method for a radiation image information reading apparatus according to the present invention and an apparatus for realizing the method will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a radiation image information reading device provided with a reading sensitivity adjusting device according to the present invention. The radiation image information reading apparatus reads out the stimulated emission light B emitted from the sheet 1 under predetermined reading conditions including the reading gain Sc of the photoelectric conversion means 20 and the reading width D0 of the reading unit 1, and obtains digital image data E1. Reading unit 1
And a reading sensitivity adjusting device 2 according to the present invention.

The reading section 1 includes an excitation light irradiating means 10 for scanning and irradiating the stimulable phosphor sheet 1 with excitation light (laser light A), and stimulated emission light emitted from the sheet 1 by irradiation of the laser light A. B is read photoelectrically and an electric signal (image signal)
, A logarithmic amplifier 26 that logarithmically amplifies the image signal E0 read by the photoelectric conversion means 20, and a logarithmically amplified image signal into digital image data (hereinafter simply referred to as “image data”) E1. A / D conversion circuit for conversion
28, a high voltage application means 25 for applying a high voltage to the photoelectric conversion means 20, and a transport means 60 capable of placing the sheet 1 and transporting the sheet 1 in the sub-scanning direction (the direction of arrow X in the figure).

The excitation light irradiating means 10 includes a laser light source 11 for emitting a laser beam A having a predetermined wavelength, a rotary polygon mirror 12 for reflecting and deflecting the emitted laser beam A, and a motor for driving the rotary polygon mirror 12 to rotate. 13. fθ lens that focuses laser light A
A laser beam A emitted from a laser light source 11 scans the sheet 1.

The photoelectric conversion means 20 includes a light guide 22 for condensing stimulated emission light B which emits by irradiation (scanning) of the laser light A with an amount of light corresponding to radiation image information stored and recorded on the sheet 1. And a photomultiplier 24 for amplifying and photoelectrically converting the condensed stimulated emission light B to obtain an image signal carrying radiation image information accumulated and recorded on the sheet 1. Note that, in this case, the reading gain of the photoelectric conversion unit 20 is synonymous with the reading gain of the photomultiplier 24.

On the other hand, the reading sensitivity adjusting device 2 according to the embodiment of the present invention comprises an averaging means 41 for obtaining an average pixel value QL of the image data E1 obtained by the reading section 1, and an average sensitivity based on the average pixel value QL. A normalizing means 42 for obtaining an index Sk, the read gain Sc of the photomultiplier 24 with respect to the average sensitivity index Sk
Means 43 for performing a predetermined operation on the basis of the above to obtain a correction sensitivity index Sk *, constant setting means for setting predetermined constants M and N
44, conversion means 45 for obtaining the sensitivity index value S0 based on the corrected sensitivity index Sk * and the constants M and N, and sensitivity index setting for setting the expected index value S1 representing the expected reading sensitivity under the above-described predetermined reading conditions. Means 46, sensitivity index value S0 and expected index value
It comprises adjusting means 50 for adjusting the reading sensitivity based on the relationship with S1.

The adjusting means 50 includes a voltage detecting means 52 for detecting a high voltage value V0 applied to the photomultiplier 24 by the high voltage applying means 25, a high voltage applied to the photomultiplier 24 and a reading gain of the photomultiplier 24. When the parameter representing the relationship with Sc is PMTK, a predetermined operation is performed to perform the high-voltage voltage value V1.
And a high voltage control means 56 for changing the high voltage applied to the photomultiplier 24.The high voltage control means 56 is connected to the high voltage application means 25 to apply the high voltage. The read sensitivity of the radiation image information reading apparatus is to be adjusted by adjusting the high voltage applied from the means 25 to the photomultiplier 24.

Next, the operation of the reading sensitivity adjusting device according to the present embodiment will be described while explaining the operation of the reading section 1 of the radiation image information reading apparatus having the above-described configuration. First, radiation solid image information is recorded on the sheet 1 under a predetermined recording condition by a radiation image information recording device (not shown) or the like. Next, the sheet 1 on which the solid image information is recorded is conveyed by the conveying means 60 in the direction of the arrow X in FIG.
0, is carried into the reading unit 1 including the photoelectric conversion unit 20 and the like, and under the predetermined reading conditions including the reading gain Sc of the photoelectric conversion unit 20 and the reading width D0 of the reading unit 1, To read solid image information.

In the reading section 1, a laser beam A emitted from a laser light source 11 is deflected in a predetermined direction by a rotating polygon mirror 12 driven at high speed by a motor 13, and the deflected laser beam A is converted into an fθ lens 14. And irradiates the sheet 1 after being reflected by the reflection optical system 15. At this time, due to the rotation of the rotary polygon mirror 12 in the direction of arrow K, the laser beam A scans the sheet 1 in the main direction of arrow Y, and the sheet 1
The main scanning and the movement of the conveying means 60 in the direction of the arrow X (sub-scanning) are combined so that the laser light A is uniformly irradiated.

From the surface of the sheet 1 irradiated with the laser beam A, stimulated emission light B according to the stored and recorded radiation image information is emitted, and the stimulated emission light B is arranged on the upper surface of the sheet 1. The light is collected by the light guide 22. A predetermined high voltage V0 determined based on the reading gain Sc is applied to the photomultiplier 24 in advance, and under this condition, the stimulated emission light collected by the light guide 22 is photoelectrically converted by the photoelectric conversion unit 24. As a result, the image signal E0 carrying the image information recorded on the sheet 1 is read. Photoelectric conversion means 20
Is read by the logarithmic amplifier 32, and the logarithmic image signal is read by the A / D conversion circuit 28 with a reading width D0 set in advance by four digits of 11 bits (digital value 0).
To 2047) is converted to image data (pixel value) E1.

The image data E1 read by the reading section 1 in this manner is input to the averaging means 41 of the reading sensitivity adjusting device 2, and the averaging means 41 averages the image data E1 in the substantially central portion of the sheet 1. After the pixel value QL is obtained, the average pixel value QL is input to the normalization means 42.

Next, in the normalizing means 42, the image data D1 representing one digit of the reading width D0 (in this embodiment, D1 =
Using (512), the calculation of Sk = QL / D1 = QL / 512 is performed to determine the average sensitivity index Sk. Further, the correction means 43 performs an operation of Sk * = Sk + Sc on the average sensitivity index Sk based on the reading gain Sc to perform the correction sensitivity index Sk *.
Ask for. Also, constants M and N are set to M = 2 and N = 4 by constant setting means 44, and S0 = M × 10 based on correction sensitivity index Sk * and constants M and N by conversion means 45.
Perform the calculation of ^{(N-Sk *)} = 2 x 10 ^{(4-Sk *) to obtain} the sensitivity index value.
Find S0. The sensitivity index value S0 is displayed at a predetermined location of the radiation image information reading device in a form (for example, as numerical information) that the operator can understand. Usually, the operator uses this numerical value as an index of the reading sensitivity of the radiation image information reading apparatus. Next, the sensitivity index value S0 is input to the high-voltage voltage value calculating means 54 of the adjusting means 50, and the expected index value S1 representing the sensitivity index expected when recording and reading are performed under the recording conditions and reading conditions is calculated. Set by the sensitivity index setting means 46,
This expected index value S1 is similarly input to the high voltage value calculating means 54. Further, the high voltage V0 applied to the photomultiplier 24 is detected by the voltage detecting means 52, and this voltage value V0 is input to the high voltage value calculating means 54.

In the present embodiment, the voltage detecting means 52 is configured to directly detect the high voltage applied to the photomultiplier. However, the voltage detecting means 52 is not necessarily limited to this. The high voltage V0 may be detected by performing conversion based on the control voltage E2 input to the high voltage applying means 25.

Next, the high-voltage calculating means 54 sets PMTK as a parameter representing the relationship between the high-voltage applied to the photomultiplier 24 and the reading gain Sc of the photomultiplier 24. V1 = V0 × 10 ^−PMTK × ^{( The} calculation of ^{log S1-log S0)} is performed to obtain the high voltage value V1. The high voltage value calculation means 54 inputs the calculation result to the high voltage control means 56,
The high voltage control means 56 controls the high voltage by inputting the control voltage E2 to the high voltage application means 25 so that the high voltage value V1 is applied from the high voltage application means 25 to the photomultiplier 24. At this time, it is desirable to monitor the high voltage applied by the voltage detecting means 52.

Next, an explanation will be given by applying actual numerical values. When the above configuration is adopted, generally, ideally, between the S value and the irradiation dose of the solid image, “S value = 200 /
Irradiation dose (mR) ". For example, assuming that the imaging dose value is 1 mR, an ideal S value (corresponding to the above-mentioned index S1) is 20 when a solid image is recorded under this condition.
It becomes 0. On the other hand, when the S value (corresponding to the sensitivity index value S0) obtained by actually taking and reading a solid image under the same conditions is 180, the sensitivity index value S0 = 180 and the index S1 = 200 are set. The high voltage voltage value V1 may be obtained by the high voltage value calculating means 54.

As described above, the sheet 1 on which the solid image is recorded under the predetermined conditions is read, and as described above, the parameter S which is unique to the radiation image information reading apparatus is used.
An index representing the reading sensitivity (sensitivity index value S0) called a value is displayed on the radiation image information reading apparatus, and the reading sensitivity can be adjusted with reference to the sensitivity index value S0. The sensitivity can be easily adjusted.

Further, the reading sensitivity adjusting method and apparatus according to the present invention can be applied not only to the case where the reading sensitivity is adjusted in one radiation image information reading apparatus as described above. For example, when a plurality of radiation image information reading apparatuses are to be adjusted to the reading sensitivity of one reference radiation image information reading apparatus, the present invention can be applied to adjusting the reading sensitivity of the remaining radiation image information reading apparatuses. it can. In this case, under the same conditions, a solid image is actually photographed and read by a plurality of radiation image information reading apparatuses to be adjusted, and the S value (the sensitivity index value described above) obtained by the reference radiation image information reading apparatus is obtained. S value expected to correspond to S0 (corresponding to the above-mentioned expected index value S1, which is referred to as "reference S value")
In the remaining radiation image information reading devices to be adjusted, the S values obtained by each radiation image information reading device are set as the above sensitivity index values S0, respectively, and the reference S value of the radiation image information reading device as a reference Is the above expected index value S1,
Further, by detecting the high voltage value V0 applied to the photomultiplier for each device and calculating the high voltage value V1, respectively, the reading sensitivity of all the radiation image information reading devices can be made substantially the same. become able to.

In the above-described embodiment, the reading sensitivity of the entire apparatus is adjusted by adjusting the high-voltage applied to the photomultiplier 24 to adjust the reading gain of the photomultiplier 24. Is not necessarily limited to this, and adjusts the reading sensitivity of the entire radiation image information reading apparatus based on the sensitivity index value S0 obtained as described above and the expected index value S1 representing the expected sensitivity index. Any means may be used.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a reading sensitivity adjusting device of a radiation image information reading device according to the present invention.

[Explanation of symbols]

 1 reading section 10 excitation light irradiation means 20 photoelectric conversion means 25 high voltage application means 41 averaging means 42 normalization means 43 correction means 44 constant setting means 45 conversion means 46 sensitivity index setting means 50 adjustment means 52 voltage detection means 54 high voltage Value calculation means 56 High voltage control means 60 Transport means

Claims (6)

[Claims] 1. A method for adjusting a reading sensitivity of a radiation image information reading apparatus for reading a radiation image information from a recording medium on which the radiation image information is recorded by a reading unit including a photoelectric conversion unit under a predetermined recording condition. The image information on the recording medium on which the solid radiation image information is recorded is read by the photoelectric conversion unit to obtain a sensitivity index value representing the reading sensitivity of the reading unit, and the reading unit to be obtained under the predetermined recording condition A reading sensitivity adjustment method for a radiation image reading apparatus, wherein the reading sensitivity of the reading unit is corrected based on an expected index value representing the reading sensitivity and the sensitivity index value. 2. The read sensitivity adjusting method according to claim 1, wherein the read sensitivity is corrected by correcting a high voltage value applied to the photoelectric conversion unit. 3. The sensitivity index value is S0, and the expected index value is
S1, V0 is the high voltage value of the photoelectric conversion means when obtaining the sensitivity index value S0, V1 is the correction value of the high voltage value to be applied to the photoelectric conversion means, and V1 is the high voltage applied to the photoelectric conversion means. When a parameter representing the relationship between the voltage and the read gain of the photoelectric conversion means is PMTK, an operation of V1 = V0 × 10 ^−PMTK × ^{(log S1−log S0)} is performed and applied to the photoelectric conversion means. 3. The method according to claim 2, wherein the high voltage value is corrected. 4. A reading sensitivity adjusting device for a radiation image information reading device for reading said radiation image information from a recording medium on which the radiation image information is recorded by a reading unit including a photoelectric conversion means, wherein the reading sensitivity adjustment device is provided under a predetermined recording condition. An index value calculating unit that reads image information on a recording medium on which the radiation solid image information is recorded by the photoelectric conversion unit and obtains a sensitivity index value representing a reading sensitivity of the reading unit; A reading sensitivity correction unit that corrects the reading sensitivity of the reading unit based on an expected index value indicating the reading sensitivity of the reading unit and the sensitivity index value to be read. Reading sensitivity adjustment device. 5. The reading apparatus according to claim 4, wherein the reading sensitivity correction unit is a unit that corrects the reading sensitivity by correcting a high voltage value applied to the photoelectric conversion unit. Sensitivity adjustment device. 6. The reading sensitivity correction means, wherein the sensitivity index value is S0, the expected index value is S1, and the high voltage voltage value of the photoelectric conversion means when the sensitivity index value S0 is obtained is V0, When the correction value of the high voltage value to be applied to the means is V1 and the parameter representing the relationship between the high voltage applied to the photoelectric conversion means and the read gain of the photoelectric conversion means is PMTK, V1 = V0 × 6. The read sensitivity adjusting device according to claim 5, wherein the read sensitivity adjusting device is a means for performing an operation of 10 ^-PMTK x ^{(log S1-log S0)} to correct a high voltage value applied to the photoelectric conversion means.