JP2001066368A - Radiation imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To update correcting data for correcting an unevenness of a strength of a detection signal of a radiation detector in a suitable form without impairing continuity of image quality of a photographed image. SOLUTION: In the case of updating correcting data of an X-ray detection signal, newly collected correcting data collected by a flat panel X-ray sensor 2 is weighted so as to become lighter than a weight of stored correcting data read from correction memories 15, 16 as newly correcting data. Thus, an influence of the newly collected correcting data on the updated newly correcting data is small. As a result, the newly correcting data is not largely changed from the correcting data, and no large difference exists in image qualities of both the X-ray images before and after updating of the correcting data. The collection of the newly collected correcting data can be conducted in a short time, and a sufficient data correcting effect is obtained by increasing updating frequency of the correcting data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation imaging apparatus provided with an array type radiation detector for detecting transmitted radiation and used in medical X-ray fluoroscopy apparatuses and industrial X-ray nondestructive inspection apparatuses. In particular, the present invention relates to a technique for updating correction data for correcting a variation in the intensity of a (radiation) detection signal output from an array-type radiation detector.

[0002]

2. Description of the Related Art Recently, in a medical or industrial X-ray imaging apparatus, a flat panel X-ray sensor (hereinafter abbreviated as "panel X-ray sensor" as appropriate) 51 as shown in FIG.
Has attracted much attention as an array-type detector for transmitted X-ray detection (for example, see W. Zhao, et al., “A flat pan
el detector for digital radiology using active mat
rixreadout of amorphous selenium, ”Proc.SPIE Vol.2
708, pp. 523-531, 1996). This panel-type X-ray sensor 51 has a configuration in which a large number of X-ray detection elements 51a having an X-ray sensitive film such as an amorphous Se film are arranged in an XY matrix on the detection surface, and is lightweight and thin. This is a two-dimensional array type X-ray detector that is also suitable for area increase.

However, in the panel type X-ray sensor 51 shown in FIG. 8, there is generally a variation in the intensity of the X detection signal (intensity unevenness) due to the unevenness in the spatial characteristics of the detection surface. In other words, offset (intensity of detection signal when X-ray is not irradiated) and sensitivity (intensity of detection signal when X-ray is irradiated with the same dose)
Is not the same for each X-ray detection element 51a, and often differs. Therefore, if an image is formed with the detected signal as it is, a remarkable artifact (false image) appears in the X-ray image.
Will appear.

Therefore, correction data for correcting the intensity unevenness of the detection signal of the panel type X-ray sensor 51 is obtained and stored in advance for each X-ray detection element 51a, and during X-ray photography,
X-ray irradiation on the subject to be imaged
The detection signal output from the line sensor 51 is subjected to arithmetic processing for correcting the variation in signal strength based on the correction data, thereby preventing the appearance of artifacts.

Further, since the intensity unevenness of the detection signal of the panel type X-ray sensor 51 changes with the passage of time (it fluctuates with time), new correction data is obtained and stored again after a certain period of time. The already-corrected correction data is updated.

[0006]

However, in the case of the above-mentioned conventional flat panel type X-ray sensor 51, the image quality of the X-ray image greatly changes before and after updating the correction data.
That is, there is a problem that discontinuity occurs over time in image quality. Since the variation with time of the intensity unevenness of the detection signal of the panel type X-ray sensor 51 is relatively large, a considerable difference occurs in the correction amount before and after updating the correction data. This is because the image qualities of both X-ray images before and after the update are considerably different.

Of course, if the correction data is updated frequently at short time intervals, the difference in image quality between the two X-ray images before and after the update of the correction data is reduced. However, usually, correction data is obtained by averaging data obtained by multiple data collections. Therefore, if the correction data is frequently updated, it takes too much time to update the correction data, which is practical. is not.

If the correction data is obtained by one data collection, it takes no time to update the correction data, but since the correction data is not accurate, the intensity unevenness of the detection signal can be sufficiently suppressed. Therefore, the correction data cannot be updated properly.

In view of the above circumstances, the present invention updates the correction data for correcting the variation in the intensity of the detection signal output from the array type radiation detector without changing the continuity of the image quality of the captured image. It is another object of the present invention to provide a radiation imaging apparatus capable of performing imaging in an appropriate manner.

[0010]

The present invention has the following configuration to achieve the above object. That is, the radiation imaging apparatus according to claim 1, a radiation irradiation unit that irradiates the subject with radiation, an array-type radiation detector for detecting transmitted radiation in which a plurality of radiation detection elements are arranged on a detection surface, Correction data storage means for storing correction data for correcting the variation in the intensity of the detection signal caused by unevenness in the locational characteristics of the detection surface of the array type radiation detector in association with each radiation detection element, A correction operation for performing an operation for correcting a variation in signal intensity of each radiation detection signal output from the array type radiation detector in accordance with the irradiation of radiation to the subject based on the correction data stored in the correction data storage means. In a radiation imaging apparatus having a processing means, a detection signal as a new acquisition correction data for updating is collected from an array type radiation detector, and correction is performed. The stored correction data is read out from the data storage means, and the new collection correction data is weighted so that both data have a smaller weight than the stored correction data, and the stored correction data is used as the new correction data. It is characterized by comprising a correction data updating means for updating.

According to a second aspect of the present invention, in the radiation imaging apparatus according to the first aspect, the correction data comprises offset correction data and sensitivity correction data, and the correction data is first stored in the correction data storage means. The initial correction data to be stored in the memory shall be the data obtained by averaging the detection signals obtained by multiple data collections for the array type radiation detector, and the new correction correction data shall be the data obtained by one data collection for the array type radiation detector. It is characterized by being configured to be the obtained detection signal.

[Operation] Next, the operation of the radiation imaging apparatus according to the present invention will be described. In the radiation imaging apparatus according to the first aspect of the present invention, first, correction data for correcting the intensity unevenness of the detection signal due to the unevenness in the spatial characteristic of the detection surface of the array type radiation detector is obtained for each radiation detecting element. The data is stored in advance in the correction data storage means in association with each radiation detection element. While the radiographing apparatus is taking an image, the correction arithmetic processing means causes the array-type radiation detector to emit radiation to the subject based on the correction data stored in the correction data storage means. As a result of performing the arithmetic processing for correcting the variation of the signal intensity on each of the output radiation detection signals, the intensity unevenness of the detection signal which causes an artifact is removed.

[0013] When the correction data is updated in the radiation imaging apparatus, the correction data updating means collects a detection signal as a new update correction data for update from the array type radiation detector as appropriate. With
The stored correction data is read out from the correction data storage means, and both data are weighted so that the newly collected correction data is lighter in weight than the stored correction data. The data is stored in the data storage means as new correction data instead of the stored correction data.

The new collected correction data is data that actually indicates the state of the detection surface at the time of updating, and may have a considerable difference in intensity from the stored correction data. However, even if there is a considerable intensity difference between the new collected correction data and the stored correction data, the new collected correction data is lighter in weight than the stored correction data, and may have an influence on the new correction data. Low, the new correction data does not drastically change from the stored correction data,
There is no significant difference in the image quality between the two captured images before and after updating the correction data.

Further, the error included in the new collection correction data is also lightly weighted, and the degree of influence of the error included in the new collection correction data on the new correction data is low. Therefore, it is not necessary to repeat the data collection many times to average a large amount of data, so that the data for new collection correction can be collected in a short time.

Further, since the weight of the new collected correction data is light, the data correction effect by one data update is small, but if the time interval for updating the correction data is shortened to increase the update frequency, A sufficient data correction effect can be obtained. Of course, even if the update frequency increases, the collection of the new collection correction data can be completed in a short time, so that it does not take too long to update the correction data.

In the case of the radiation imaging apparatus according to the second aspect,
Based on the offset correction data and the sensitivity correction data, the radiation detection signal is corrected for both offset unevenness and sensitivity unevenness. In addition, the initial correction data initially stored in the correction data storage means is accurate because it is obtained by averaging detection signals obtained by a plurality of data acquisitions for the array type radiation detector. In addition, since the new collection correction data is a detection signal obtained by one data collection for the array type radiation detector, data collection can be performed in a very short time.

[0018]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of an X-ray imaging apparatus according to an embodiment, and FIG.
FIG. 3 is a schematic diagram showing a configuration of an imaging system of a line imaging apparatus, and FIG.
FIG. 2 is a schematic plan view showing a detection surface of a flat panel X-ray sensor for line detection.

As shown in FIG. 1, an X-ray imaging apparatus according to an embodiment includes an X-ray tube 1 for irradiating a subject M with X-rays and a flat panel X-ray sensor (two-dimensional array) for detecting transmitted X-rays. Type X
(A line detector) 2 is disposed to face the subject M placed on the top 3. Further, on the control system side at the subsequent stage of the flat panel type X-ray sensor 2, signal processing is performed based on a detection signal output from the flat panel type X-ray sensor 2 along with X-ray irradiation to the subject M, It is configured so that an X-ray image of the subject M can be obtained. Less than,
The configuration of each part of the apparatus according to the embodiment will be specifically described.

The X-ray tube 1 for X-ray irradiation is controlled by an irradiation control unit 4 including a high-voltage generator 5 and the like in accordance with set irradiation conditions such as a tube voltage and a tube current.
Are configured to irradiate the patient M with X-rays.

As shown in FIG. 3, a flat panel X-ray sensor 2 for detecting transmitted X-rays has an extremely large number of X-ray detecting elements 2a on an XY matrix (1024 × 102
After the charge signals accumulated in the respective X-ray detection elements 2a are sequentially read out with the X-ray irradiation under the control of the reading control unit 6, the signals are amplified and A / D-controlled.
After the conversion, the signal is output to the control system as a detection signal for X-ray image creation.

With respect to the top 3 for mounting the subject, the control of the top driving unit 7 enables the X
The table 3 is configured to move by a required distance in each of the directions (horizontal), Y (vertical = body axis direction of the subject M), and Z (vertical).

The irradiation controller 4, the read controller 6,
The control by the top driving unit 7 is performed by the operation console 8.
Shooting control unit 9 according to the input operation from the camera and the shooting progress status
This is performed in accordance with a command signal appropriately sent from the controller.

On the other hand, the X-ray imaging apparatus according to the embodiment has a detection signal memory (original image memory) 1 for storing a detection signal output from the flat panel type X-ray sensor 2 with X-ray irradiation.
0, a signal processing unit 11 for performing necessary signal processing on the detection signal, and an X-ray image memory 12 for storing an X-ray image obtained by the necessary signal processing. A display monitor 13 for displaying the obtained X-ray image, and an image printer (laser imager) 14 for printing the X-ray image stored in the X-ray image memory 12 onto a film and outputting it as an image photograph. Also,
The signal processing unit 11 performs so-called image processing signal processing such as edge enhancement, filtering, or digital subtraction (DSA) as necessary signal processing.
It also sets and updates correction data for correcting the detection signal output from the line sensor 2 and corrects the intensity unevenness of the (X-ray) detection signal based on the correction data.

Subsequently, a flat panel type X-ray sensor (X
The configuration of the line surface sensor 2 will be specifically described. FIG. 4 is a schematic sectional view of the X-ray sensor section of the flat panel X-ray sensor 2, and FIG. 5 is a block diagram showing the entire configuration of the flat panel X-ray sensor 2.

The flat panel type X-ray sensor 2 has a semiconductor film 21 which is an X-ray sensitive film (for example, an amorphous Se thick film) in which carriers are generated by incidence of X-rays.
A voltage application electrode 22 provided on the surface of the semiconductor film 21 on the X-ray incidence side, a carrier collection electrode 23 provided on the back surface of the semiconductor film 21 on the non-X-ray incidence side, and collection on the carrier collection electrode 23. A capacitor Ca for accumulating charges for storing carriers and a thin film transistor (TFT) of a switch element 24 for extracting charges stored in the capacitor Ca which is normally off (cut off) for extracting charges are provided. In a state where a bias voltage is applied, generated carriers accompanying the X-ray irradiation are sent from the carrier collecting electrode 23 to the capacitor Ca and accumulated, and the switch element 24 is turned on (connected) at the read timing. The stored charges are read out as (X-ray) detection signals. Therefore, the flat panel X-ray sensor 2 has a direct X-ray detection element 2a composed of the semiconductor film 21 and a part of the voltage application electrode 22, the carrier collection electrode 23, the switch element 24, and the capacitor Ca. It is a conversion type X-ray sensor.

In the flat panel X-ray sensor 2, the source of the thin film transistor for the switch element 24 of the X-ray detecting element 2a is connected to the horizontal (X) readout wiring 25, and the gate is connected to the vertical (Y) direction. It is connected to the read wiring 26. The read wiring 25 is connected to a multiplexer 28 via a preamplifier group (charge-voltage converter group) 27, and the read wiring 26 is connected to the gate driver 2.
9 is connected. In the preamplifier group 27, 1
One preamplifier (charge-voltage converter) is connected to each of the readout wirings 25.

In the case of the flat panel X-ray sensor 2, a scanning signal for signal extraction is sent from the read control unit 6 to the multiplexer 28 and the gate driver 29. Each X-ray detection element 2a is specified by X
Addresses (for example, 0 to 1023) sequentially assigned to each X-ray detection element 2a along the array in the direction and the Y direction
, And the scanning signal for extraction is a signal for designating an X-direction address or a Y-direction address, respectively.

As a voltage for taking out is applied from the gate driver 29 to the readout wiring 26 in the Y direction in accordance with the scanning signal in the Y direction, each X-ray detection element 2a is selected in a column unit. When the multiplexer 28 is switched in accordance with the scanning signal in the X direction, the electric charge accumulated in the capacitor Ca of the X-ray detecting element 2a in the selected column is passed through the preamplifier group 27 and the multiplexer 28 in order and stored in the detection signal memory at the subsequent stage. It is sent to 10 as an (X-ray) detection signal. The detection signal memory 10 is a frame memory in which detection signals of the respective X-ray detection elements 2a are stored in memory cells of the same address with the same addressing as that of the flat panel X-ray sensor 2.

In the case of the flat panel type X-ray sensor 2, a preamplifier group 27, a multiplexer 28, a gate driver 29 and, if necessary, an AD converter (not shown)
And the like are also installed integrally, and are configured to be further integrated. However, all or a part of the preamplifier group 27, the multiplexer 28, the gate driver 29, the AD converter, and the like may be separately provided.

In the flat panel X-ray sensor 2 described above, there is still unevenness in the intensity of the detection signal due to unevenness in the spatial characteristics of the detection surface. Specifically, there are variations in the offset (output when X-rays are not irradiated) and sensitivity (gain = X-ray conversion rate) between the X-ray detection elements 2a. In the case of the apparatus according to the embodiment, as shown in FIG. 6, the offset of each X-ray detection element 2a is X-ray irradiation amount 0 (X
(A non-irradiation state), the intensity itself of each detection signal output from the flat panel X-ray sensor 2 is used, and the sensitivity of each X-ray detection element 2a is a constant X-ray irradiation amount Xt
A value obtained by subtracting an offset from the intensity of each detection signal output from the flat panel X-ray sensor 2 in the (X-ray irradiation state) is used.

Of course, as shown in FIG. 6, the intensity of each detection signal output from the flat panel X-ray sensor 2 with the X-ray exposure amount of 0 and the blank state where the subject M is not placed on the top 3 , The gradient (corresponding to the X-ray conversion rate) of a line segment P connecting the intensity of each detection signal output from the flat panel X-ray sensor 2 with a constant X-ray exposure Xt
The sensitivity may be obtained for each a and used as the sensitivity.

The signal processing unit 11 of the X-ray imaging apparatus according to the embodiment is used for correction for correcting offset and sensitivity variations due to unevenness in the spatial characteristics of the detection surface of the flat panel X-ray sensor 2. The signal processing unit 11 includes an offset correction memory 15 and a sensitivity correction memory 16 for storing data.
An initial correction data setting unit 17 for obtaining and storing both initial correction data at 16 and a correction data updating unit 18 for updating the correction data stored in each of the correction memories 15 and 16 to new correction data. And a flat panel X during photographing based on the data stored in the correction memories 15 and 16.
A correction arithmetic processing unit 19 for performing arithmetic processing for correcting the intensity unevenness of each detection signal output from the line sensor 2 is provided.

Hereinafter, a configuration for correcting the unevenness of the intensity of the detection signal of the flat panel type X-ray sensor 2 will be specifically described.

The initial correction data setting unit 17 outputs a detection signal obtained by n (for example, 64) data collections for the flat panel X-ray sensor 2 in the X-ray non-irradiation state for each X-ray detection element 2a. Then, the data is averaged (averaged) and stored in the offset correction memory 15 as initial offset correction data of each X-ray detection element 2a. That is, if the k-th detection signal of the X-ray detection element 2a at the address i in the X direction and the address j in the Y direction is Xk (i, j), the initial offset correction data A
(i, j) is as follows.

A (i, j) = [X1 (i, j) + X2 (i, j) + .. +
Xk (i, j) + .. + Xn (i, j)] / n

The initial correction data setting section 17 subtracts an offset amount from each detection signal obtained by n (for example, 64) data collections for the flat panel X-ray sensor 2 in the X-ray irradiation state. The X-ray detection elements 2a are averaged (averaged) and stored in the sensitivity correction memory 16 as initial sensitivity correction data of each X-ray detection element 2a. That is, the X-direction address i
The detection signal obtained at the k-th time of the X-ray detection element 2a at the address j in the Y direction address is represented by Yk (i, j) = Xk (i, j) -A (i, j).
Then, the initial sensitivity correction data B (i, j) is as follows.

B (i, j) = [Y1 (i, j) + Y2 (i, j) + .. +
Yk (i, j) + ·· + Yn (i, j)] / n

By averaging the detection signals for n times as described above, the correction data becomes accurate due to noise reduction or the like, and the detection signals can be accurately corrected.

The correction data updating unit 18 performs one time (m) for the flat panel X-ray sensor 2 in the X-ray non-irradiation state.
), The detected signal obtained in the data collection is used as new collection correction data, the stored offset correction data corresponding to each detection signal is read, and the new collection correction data is compared with the stored correction data. The data is weighted so that the weights become lighter and then added, and then updated and stored in the offset correction memory 15 as new offset correction data. That is, the X-ray detecting element 2 at the address i in the X direction and the address j in the Y direction
Assuming that the detection signal of a is Xm (i, j), the new offset correction data in the offset correction memory 15 is updated as follows.

A (i, j) ← A (i, j) · (n−1) / n + Xm (i, j) / n

That is, the detection signal X of the new collection correction data
m (i, j) is weighted as small as 1 / n, and the stored offset correction data A (i, j) is weighted as large as (n-1) / n.

Further, the correction data updating unit 18 subtracts an offset from each detection signal obtained by one (m) data collection for the flat panel X-ray sensor 2 in the X-ray irradiation state. Obtain as new collection correction data, read the stored sensitivity correction data corresponding to each detection signal, and weight both data so that the new collection correction data is lighter in weight than the stored correction data. After addition, the data is updated and stored in the offset correction memory 16 as new sensitivity correction data. That is, if the new collection correction data of the X-ray detecting element 2a at the address i in the X direction and the address j in the Y direction is Ym (i, j) = Xm (i, j) -A (i, j), The sensitivity correction data is updated as follows. Note that this A (i,
j) is new offset correction data after updating and storage.

B (i, j) ← B (i, j) · (n−1) / n + Ym (i, j) / n

That is, the new collected correction data Ym (i, j) is weighted as small as 1 / n, and the stored sensitivity correction data B (i, j) is assigned (n-1) / n They give great weight.

Further, in the case of the embodiment, the correction data updating section 18 updates both the correction data A (i, j) and B (i, j) when a predetermined time TM determined by the timer 20 elapses. Configuration. The predetermined time TM is, for example, 0
A time between ３０30 minutes is chosen. The predetermined time TM does not need to be always constant, and the predetermined time TM may become longer or shorter in the range of 0 to 30 minutes as the apparatus operation time elapses.

The correction operation processing section 19 is a memory for both corrections 1
The correction data A (i, j) and B stored in
Based on (i, j), an arithmetic process for correcting signal intensity unevenness is performed on the detection signal X (i, j) output from the flat panel X-ray sensor 2 during X-ray imaging. That is, assuming that the detection signal of the X-ray detecting element 2a at the address i in the X direction and the address j in the Y direction is X (i, j), the calculation result is as follows.

X (i, j) ← [X (i, j) −A (i, j)] · α / B (i, j)

The above-mentioned symbol α is an adjustment coefficient for making the signal level easy to handle, and a value such as 1000 or 2000 is usually selected.

That is, by subtracting the offset correction data A (i, j) from the detection signal X (i, j), the detection signal X (i, j) is obtained.
The effect of the offset variation is canceled from (i, j), and the sensitivity variation is canceled by dividing by B (i, j). Thus, the correction operation processing unit 1
9 corrects both the offset unevenness and the sensitivity unevenness of the detection signal, so that the intensity unevenness of the detection signal is sufficiently eliminated.

Next, the process of setting and updating correction data in the X-ray imaging apparatus of the embodiment having the above-described configuration will be described with reference to the drawings. FIG. 7 is a flowchart showing the progress of setting and updating of correction data in the apparatus of the embodiment.

[Step S1] Initial offset correction data A (i, j) is obtained by the initial correction data setting unit 17 and stored in the offset correction memory 15.

[Step S2] Initial sensitivity correction data B (i, j) is obtained by the initial correction data setting unit 17 and stored in the sensitivity correction memory 16.

[Step S3] When the subject M is set at the imaging position and X-ray imaging is started, the correction data A stored in the two correction memories 16 by the correction arithmetic processing unit 19
Based on (i, j) and B (i, j), arithmetic processing for correcting offset unevenness and sensitivity unevenness of a detection signal output from the flat panel X-ray sensor 2 is performed, and finally an X-ray image Is obtained.

[Step S4] If it is necessary to update the correction data after the lapse of the predetermined time TM set by the timer 20, the process proceeds to the next step S5. Predetermined time TM
If has not elapsed and it is not necessary to update the correction data, the process proceeds to step S7.

[Step S5] Correction data updating section 18
To obtain new offset correction data A (i, j) and update the data in the offset correction memory 15.

[Step S6] Correction data updating section 18
, New sensitivity correction data B (i, j) is obtained, and the data in the sensitivity correction memory 16 is updated.

[Step S7] If the X-ray photography is to be continued, the flow returns to step S3 to execute the X-ray photography. X
If the line imaging is not performed, the operation of the apparatus ends.

As described in detail above, according to the X-ray imaging apparatus of the embodiment, when updating the correction data for correcting the intensity unevenness of the detection signal from the flat panel X-ray sensor 2, a new The two data are weighted and then added to obtain new correction data for updating so that the collected correction data is lighter in weight than the stored correction data. Light new correction data has a low influence on the new correction data, and the updated and stored new correction data does not significantly change from the stored correction data. There is no significant difference in the image quality of the X-ray image.

In addition, the error included in the new collected correction data also has a low influence on the new correction data. Therefore, one update of the correction data requires only one data collection. The collection of the correction data is completed in a short time. Further, since the collection of the new collection correction data per update can be completed in a short time, even if the frequency of correction data update is increased to obtain a sufficient data correction effect, the correction data can be updated. It doesn't take too long.

The present invention is not limited to the above embodiment, but can be modified as follows.

(1) In the case of the embodiment, the flat panel type X
Although the detection signal of the line sensor is temporarily stored in the detection signal memory, an apparatus having a configuration in which there is no detection signal memory and the detection signal is directly taken into the signal processing unit is mentioned as a modified example.

(2) In the case of the embodiment, the detection signal of the new collection correction data is weighted by 1 / n, and the stored offset correction data is weighted by (n-1) / n. , The weighting associated with the number of averaging (n) is performed. For example, an apparatus having a configuration in which the weighting is independent of the number of averaging is given as a modified example.

(3) In the case of the embodiment, the number of times of data collection of the new collection correction data is one. However, the number of times of data collection of the new collection correction data is set to a time which does not hinder X-ray imaging. If so, the number may be about several times instead of once.

(4) In the embodiment, the data for correction is updated periodically, but when the operator feels it necessary, the data for correction is updated by an input operation from a console or the like. A configuration in which execution is performed irregularly, or a configuration in which periodic execution and irregular execution can be selected may be used.

(5) The flat panel type X-ray sensor of the embodiment is a two-dimensional array type in which a large number of X-ray detecting elements are arranged vertically and horizontally. May be a one-dimensional array type in which only one line is arranged. The flat panel X-ray sensor of the embodiment is a direct conversion type, but is an indirect conversion type sensor in which incident X-rays are first converted into light, and then converted light is converted into an electric signal. Is also good.

(6) The X-ray imaging apparatus of the embodiment may have the configuration of an X-ray CT apparatus in addition to the configuration of an X-ray fluoroscopy apparatus. The radiation targeted by the present invention includes, for example, neutron rays and gamma rays in addition to X-rays.

[0068]

As described in detail above, according to the radiation detecting apparatus of the first aspect, when updating the correction data for correcting the intensity unevenness of the radiation detection signal, the data is collected from the array type radiation detector. The updated new collected correction data for update is weighted so that the weight is lower than the stored correction data read from the correction data storage means, and then added together for update. The new correction data, which is lighter in weight than the stored correction data, has a lower influence on the new correction data, and the updated new correction data is stored. Since there is no drastic change from the correction data, there is no large difference in the image quality between the two captured images before and after the update of the correction data.

The error included in the new collection correction data is also lightly weighted, and the error included in the new collection correction data has a low influence on the new correction data. It is not necessary to repeatedly collect data many times to obtain and average a large amount of data, so that the collection of the new collection correction data can be completed in a short time, and the data update does not take too much time. In addition, since the collection of the new collection correction data is completed in a short time and the data update does not take too much time, the update frequency of the correction data is increased and a sufficient data correction effect can be obtained.

That is, according to the radiation imaging apparatus of the first aspect of the present invention, the update of the correction data for correcting the intensity unevenness of the detection signal output from the array type radiation detector is performed by the photographed image. It can be performed in an appropriate manner without losing the continuity of the image quality.

According to the radiation imaging apparatus of the second aspect of the present invention, since both the offset unevenness and the sensitivity unevenness of the radiation detection signal are corrected, the intensity unevenness of the radiation detection signal is sufficiently eliminated. Further, since the initial correction data is accurate data obtained by averaging detection signals obtained by a plurality of data collections, the intensity unevenness of the radiation detection signal is sufficiently eliminated. In addition, since the newly collected data is a detection signal obtained by one data collection, data collection can be performed in a very short time.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of an X-ray imaging apparatus according to an embodiment.

FIG. 2 is a schematic diagram illustrating a schematic configuration of an imaging system of the X-ray imaging apparatus according to the embodiment.

FIG. 3 is a schematic plan view showing a detection surface of a flat panel X-ray sensor of the apparatus of the embodiment.

FIG. 4 is a schematic sectional view showing an X-ray sensor section of the flat panel type X-ray sensor.

FIG. 5 is a block diagram showing an overall configuration of a flat panel X-ray sensor.

FIG. 6 is a graph for explaining offset / sensitivity of a detection signal of a flat panel X-ray sensor.

FIG. 7 is a flowchart showing the progress of setting and updating of correction data in the apparatus according to the embodiment.

FIG. 8 is a diagram showing an arrangement of X-ray detection elements in an X-ray sensor of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... X-ray tube 2 ... Flat panel type X-ray sensor 2a ... X-ray detection element 15 ... Offset correction memory 16 ... Sensitivity correction memory 17 ... Initial correction data setting unit 18 ... Correction data update unit 19 ... Correction calculation Processing unit M ... subject

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 2G088 EE01 EE27 FF02 GG21 JJ05 KK21 LL12 LL15 LL17 LL28 4C093 AA01 AA29 CA10 EB13 EB17 ED06 ED07 EE01 EE08 FC03 FC16 FC18 FC19 FD01 FD05 AFF18A06 FF05 A11 BA05 CB05 FB08 FB09 FB13 FB16 GA10

Claims (2)

[Claims] 1. A radiation irradiating means for irradiating a subject with radiation, an array-type radiation detector for detecting transmitted radiation in which a plurality of radiation detection elements are arranged on a detection surface, and a detection surface of the array-type radiation detector Correction data storage means for storing correction data for correcting the variation in the intensity of the detection signal caused by the spatial characteristic unevenness of each of the radiation detection elements, and correction data storage means for storing the correction data, Radiographic imaging comprising a correction arithmetic processing means for performing arithmetic processing for correcting variations in signal intensity for each radiation detection signal output from the array type radiation detector in accordance with the irradiation of the subject with radiation based on the corrected data. The apparatus collects a detection signal as a new collection correction data for update from the array type radiation detector and stores the detection signal as a stored correction data from the correction data storage means. The data is read out, and the new collected correction data is weighted so that the new correction data becomes lighter than the stored correction data. A radiation imaging apparatus comprising data updating means. 2. The radiation imaging apparatus according to claim 1, wherein the correction data comprises offset correction data and sensitivity correction data, and the initial correction data stored first in the correction data storage means is an array type radiation. The detection signal obtained by a plurality of data collections for the detector is averaged, and the new collection correction data is configured to be the detection signal obtained by a single data collection for the array type radiation detector. Radiation imaging device.