JP2017006503A - Radiographic imaging system and radiographic imaging device - Google Patents

Abstract

Radiation imaging system and radiation capable of accurately recognizing when non-uniformity of sensitivity occurs in scintillator due to accumulated exposure dose, and promptly performing gain calibration for radiation imaging apparatus An image capturing apparatus is provided.
An irradiation dose obtained for each region Rn when a detection unit P of a radiographic imaging apparatus 1 including a scintillator 3 and a plurality of radiation detection elements 7 arranged two-dimensionally is virtually divided. The statistical value Dlag_st of the signal value of the resulting lag is calculated, the accumulated dose Σdst for each region Rn is updated and stored, and the absolute value | ΔΣdst | of the difference between the accumulated doses Σdst between the regions Rn is calculated. When it is determined that there is an absolute value | ΔΣdst | that is equal to or larger than the set threshold value ΔΣdth in the calculated absolute value | ΔΣdst |, the radiographic imaging apparatus 1 is notified to urge execution of gain calibration.
[Selection] Figure 8

Description

  The present invention relates to a radiographic image capturing system and a radiographic image capturing device, and more particularly to a radiographic image capturing system including a radiographic image capturing device including a scintillator.

  At the time of radiographic image capturing, radiation such as X-rays irradiated through a subject such as a patient is converted into electromagnetic waves such as visible light by a scintillator and irradiated to a plurality of radiation detection elements arranged in a two-dimensional form to detect radiation. Various radiographic imaging devices (Flat Panel Detector: FPD) have been developed, which are converted into electrical signals corresponding to the dose of radiation irradiated through the subject (ie, the amount of electromagnetic waves corresponding to the element) and read out as image data. Have been introduced in hospitals and other facilities.

  And since radiation is irradiated to the scintillator of a radiographic imaging apparatus for every imaging | photography, a scintillator deteriorates according to the accumulated dose of radiation, ie, accumulated exposure dose, and sensitivity falls. Then, in the scintillator, sensitivity unevenness occurs between the region where the cumulative exposure dose is relatively large and the sensitivity is reduced, and the region where the cumulative exposure dose is relatively small and the deterioration, i.e., the sensitivity reduction has not progressed so much. When close to each other, the above-mentioned sensitivity unevenness is visually recognized as unevenness on the image (that is, so-called image unevenness) in the radiographic image generated based on the image data read out by the radiographic apparatus. Can occur. Accordingly, gain calibration for calibrating the gain correction value of the radiation detection element is usually performed in response to the sensitivity reduction due to deterioration of the scintillator.

  The gain calibration of the radiation image capturing apparatus may be configured to be performed periodically, for example. However, for example, in a relatively small clinic, the frequency of performing imaging using a radiographic imaging device is not so high, and the decrease in sensitivity due to deterioration of the scintillator of the radiographic imaging device has not progressed so much, but periodically. There is a problem that it is necessary to perform gain calibration of the radiation image capturing apparatus. Further, even in a relatively large hospital or the like, it is necessary to periodically perform gain calibration even for a radiographic imaging apparatus that is not frequently used, for example.

  In addition, in order to determine whether or not the gain calibration of the radiographic imaging apparatus is necessary, at present, the radiographic imaging apparatus is regularly and uniformly (ie, to the radiographic imaging apparatus) with no subject interposed. In some cases, it is configured to take a radiation image by irradiating radiation of substantially the same dose over the entire surface. However, in order to determine whether or not the gain calibration of the radiographic imaging device is necessary, there is a problem that it takes time and effort to shoot an image by irradiating radiation each time.

  Therefore, for example, in Patent Document 1, radiation that has passed through a subject such as a patient is detected by a radiographic imaging device based on the radiographic image information detected by the radiographic imaging device, and the detected radiographic image information is accumulated for each imaging. The cumulative exposure dose is calculated, and the calculated cumulative exposure dose is compared with the allowable cumulative exposure dose of the radiographic imaging device. For example, when the cumulative exposure dose exceeds the allowable cumulative exposure dose, A radiation image capturing system that issues a warning prompting replacement or maintenance of a radiation image capturing apparatus has been disclosed as there is a risk of image quality degradation due to a decrease in sensitivity of the image capturing apparatus.

  If constituted in this way, it is not necessary to irradiate radiation to the radiographic imaging device for the necessity determination of gain calibration as described above, and using radiographic image information obtained at the time of imaging, that is, image data, etc. It is possible to know how much the sensitivity reduction of the scintillator has progressed, and it is possible to determine the necessity of maintenance such as gain calibration.

JP 2009-34484 A

  However, in a portion where radiation has directly reached the radiographic imaging apparatus without passing through the subject (that is, a so-called blank portion), when the amount of radiation that has reached (that is, the exposure dose) exceeds a predetermined dose, Radiation image information, that is, image data may be saturated (that is, a maximum value that can be output is output), but if image data is saturated, it is actually based on such image data. It is not possible to calculate how much radiation has been irradiated (ie exposure dose).

  Also, for example, in the case of the scintillator of the radiographic image capturing apparatus, when the deterioration has progressed uniformly and the sensitivity has decreased, the image has been photographed because there is not much difference in the degree of sensitivity decrease between each region of the scintillator. On the radiographic image, image unevenness due to uneven sensitivity of the scintillator is not visually recognized. However, even when the image unevenness is not visually recognized in this way, in the radiographic imaging system described in Patent Document 1, if the cumulative exposure dose of the radiographic imaging device exceeds the allowable cumulative exposure dose, A warning will be issued to encourage maintenance.

  In addition, for example, even in the case where a certain area of the scintillator of the radiographic image capturing apparatus is deteriorated and sensitivity is lower than that of other areas, and unevenness in the radiation image occurs due to uneven sensitivity of the scintillator, it is described in Patent Document 1. In the radiographic imaging system, if the cumulative exposure dose of the radiographic imaging device does not exceed the allowable cumulative exposure dose, a warning prompting to perform maintenance of the radiographic imaging device, that is, gain calibration or the like will not be given. . However, this cannot prevent the image unevenness from being visually recognized in the radiation image due to the sensitivity unevenness generated in the scintillator due to the accumulated exposure dose.

  The present invention has been made in view of the above problems, and when a nonuniformity in sensitivity occurs in the scintillator due to the accumulated exposure dose, it is accurately recognized, and gain calibration is performed for the radiographic image capturing apparatus. An object of the present invention is to provide a radiographic image capturing system and a radiographic image capturing apparatus that can accurately prompt the user.

In order to solve the above problems, the radiographic imaging system and radiographic imaging apparatus of the present invention are:
A radiographic imaging apparatus comprising a scintillator and a plurality of radiation detection elements arranged two-dimensionally;
In a state where radiation is not irradiated after imaging by the radiographic imaging device for each of the regions when the plurality of the radiation detection elements arranged in a two-dimensional array of the radiographic imaging device are virtually divided into a plurality of regions. The statistical value of the signal value of the lag caused by the irradiation dose obtained for each of the radiation detection elements is calculated, and the statistical value of the exposure dose in the region based on the statistical value of the signal value of the lag for each of the calculated regions A value is calculated, and for each region, the calculated statistical value of the radiation dose is added to a cumulative radiation dose that is an integrated value of statistical values of the radiation dose calculated in the past, and a cumulative radiation dose for each region is calculated. Updating means for updating
Storage means for storing the cumulative exposure dose for each of the updated areas;
A calculating means for calculating an absolute value of a difference between the accumulated doses between the regions;
A judging means for judging whether or not an absolute value of a difference equal to or larger than a set threshold exists in the calculated absolute value of the difference;
An informing means for informing the radiographic imaging apparatus to execute gain calibration when the determining means determines that the absolute value of the difference equal to or greater than the threshold is present in the absolute value of the difference;
It is characterized by providing.

Moreover, the radiographic imaging system and radiographic imaging device of the present invention are:
A radiographic imaging apparatus comprising a scintillator and a plurality of radiation detection elements arranged two-dimensionally;
In a state where radiation is not irradiated after imaging by the radiographic imaging device for each of the regions when the plurality of the radiation detection elements arranged in a two-dimensional array of the radiographic imaging device are virtually divided into a plurality of regions. The statistical value of the signal value of the lag caused by the irradiation dose obtained for each of the radiation detection elements is calculated, and the statistical value of the exposure dose in the region based on the statistical value of the signal value of the lag for each of the calculated regions A calculating means for calculating a value;
The difference in the statistical value of the exposure dose between the areas is calculated, and the difference in the statistical value of the exposure dose between the calculated areas is set to the cumulative value of the difference in the statistical value of the exposure dose between the areas calculated in the past. In addition, update means for updating the cumulative value of the difference in the statistical value of the exposure dose between the regions,
Storage means for storing a cumulative value of a difference in statistical values of exposure dose between the updated areas;
In the cumulative value of the difference between the statistical values of the exposure dose between the regions, a determination means for determining whether or not the absolute value of the cumulative value of the difference equal to or more than a set threshold exists,
When the determination means determines that a cumulative value of a difference whose absolute value is greater than or equal to the threshold value is present in the cumulative value of the difference, a notification that prompts execution of gain calibration for the radiographic imaging device Notification means to perform;
It is characterized by providing.

  According to the radiation image capturing system and the radiation image capturing apparatus of the system as in the present invention, when the sensitivity unevenness occurs in the scintillator due to the accumulated exposure dose, it is accurately recognized and the gain calibration is performed for the radiation image capturing apparatus. It is possible to promptly promote to perform.

  Then, the user who has received the notification performs gain calibration by himself, calls a service person to perform gain calibration, or sends the radiographic imaging apparatus to the manufacturer, etc. Gain calibration can be performed accurately, and it is possible to accurately prevent image unevenness due to the sensitivity variation of the scintillator from being visible in the radiographic image captured using the radiographic image capturing apparatus. It becomes possible to do.

It is a perspective view which shows the external appearance of the radiographic imaging apparatus which concerns on this embodiment. It is sectional drawing which follows the XX line of FIG. It is a block diagram showing the equivalent circuit of a radiographic imaging apparatus. It is a figure which shows the example in which a radiographic imaging apparatus is used for imaging | photography in an imaging room. It is a figure which shows the example by which a radiographic imaging apparatus is brought into a hospital room etc. and imaging is performed. It is a timing chart explaining the timing etc. when ON voltage is applied to each scanning line of a radiographic imaging device at the time of imaging. FIG. 7 is a timing chart showing that offset data reading processing is performed by repeating the processing sequence shown in FIG. 6. FIG. It is a figure which shows an example of the method of dividing | segmenting the detection part of a radiographic imaging apparatus into a some area | region virtually. It is a graph showing the relationship between the radiation dose and the signal value of lag. (A) It is a figure showing the example of a structure of the radiographic imaging system concerning this embodiment, (B) It is a block diagram showing the structure of a console. It is a graph showing that the generation amount per unit time of lag decreases as time passes. It is a figure which shows the example which divided | segmented the detection part of the radiographic imaging apparatus into the some area | region virtually by the method of division different from FIG. It is a figure showing an example of the state where the shading appeared on the radiographic image in gradation.

  Embodiments of a radiation image capturing system according to the present invention will be described below with reference to the drawings.

  In the following description, gain calibration is performed by displaying on a display unit or generating sound by using a computer other than the radiographic imaging apparatus (that is, a computer separate from the radiographic imaging apparatus) belonging to the radiographic imaging system. However, the radiographic imaging apparatus performs all the processing, and the indicator 40 (see FIG. 1 to be described later) of the radiographic imaging apparatus is turned on and blinked in a predetermined color. Alternatively, the above notification may be performed by displaying on a display unit (not shown) such as a liquid crystal display provided in the radiographic imaging apparatus or by generating sound from a speaker (not shown). In this case, the control means 22 of the radiographic image capturing apparatus 1 described later functions as an informing means described later for performing notification for prompting execution of gain calibration for the radiographic image capturing apparatus via the indicator 40, the display unit, the speaker, and the like. Will do.

  In the following, a case where the radiographic image capturing apparatus is a so-called portable type in which the sensor panel SP is housed in the housing 2 will be described, but the sensor panel Sp is formed integrally with a support base or the like. The present invention can also be applied to a so-called dedicated machine type (also referred to as an installation type) radiographic imaging apparatus.

[Radiation imaging equipment]
A basic configuration of the radiographic image capturing apparatus according to the present embodiment will be briefly described. FIG. 1 is a perspective view showing an external appearance of the radiographic image capturing apparatus, and FIG. 2 is a cross-sectional view taken along line XX of FIG. In this embodiment, the radiographic imaging device 1 is configured by housing a sensor panel SP including a scintillator 3 and a sensor substrate 4 in a housing 2 as shown in FIGS. 1 and 2. ing. In this embodiment, the housing | casing 2 is formed by obstruct | occluding the opening part of the both sides of 2 A of hollow square cylindrical housing main-body parts which have the radiation-incidence surface R with lid | cover members 2B and 2C.

  As shown in FIG. 1, a power switch 37, a changeover switch 38, a connector 39, an indicator 40, and the like are arranged on the lid member 2B on one side of the housing 2. In the present embodiment, an antenna 41 (see FIG. 3 to be described later) for communicating with an external device in a wireless manner is provided, for example, on the opposite side surface of the housing 2. In addition, power can be supplied from the outside via the connector 39, or communication with an external device can be performed in a wired manner.

  As shown in FIG. 2, a base 31 is disposed in the housing 2, and a sensor substrate 4 is provided on the radiation incident surface R side of the base 31 via a lead thin plate (not shown). It has been. A scintillator 3 that converts irradiated radiation into light such as visible light is provided on the scintillator substrate 34 on the upper surface side of the sensor substrate 4, and the scintillator 3 is provided in a state of facing the sensor substrate 4 side. Yes. Further, on the lower surface side of the base 31, a PCB substrate 33 on which electronic components 32 and the like are arranged, a battery 24, and the like are attached.

  In the present embodiment, the sensor panel SP is formed in this way. In addition, a buffer material 35 is provided between the sensor panel SP and the side surface of the housing 2. In the present embodiment, the scintillator 3 is a scintillator made of a columnar crystal of a phosphor obtained by growing a phosphor in which a luminescent center substance is activated in a matrix material such as CsI: Tl. The scintillator 3 may be a so-called coating-type scintillator formed by applying a paste-like phosphor to the scintillator substrate 34 or the like, for example.

  FIG. 3 is a block diagram showing an equivalent circuit of the radiation image capturing apparatus. As shown in FIG. 3, in the radiographic imaging apparatus 1, a plurality of radiation detection elements 7 are arranged in a two-dimensional shape (matrix shape) on a sensor substrate (not shown), and the plurality of radiation detection elements 7 are two-dimensionally arranged. The entire region arranged in a line, that is, the region indicated by the alternate long and short dash line in FIG.

  Each radiation detection element 7 has an electric charge corresponding to the dose of the irradiated radiation (more precisely, the electromagnetic wave irradiated when the radiation detection element 7 is irradiated with an electromagnetic wave obtained by converting the irradiated radiation by the scintillator 3. The electric charge according to the quantity of light) is generated. In the present embodiment, a photodiode is used as the radiation detection element 7. However, for example, a phototransistor, a CCD (Charge Coupled Device) image sensor, or the like may be used.

  A bias line 9 is connected to each radiation detection element 7, and the bias line 9 is connected to a connection 10. The connection 10 is connected to a bias power supply 14 so that a reverse bias voltage is applied from the bias power supply 14 to each radiation detection element 7 via the bias line 9 and the like.

  Each radiation detection element 7 is connected to a thin film transistor (hereinafter referred to as TFT) 8 as a switch element, and the TFT 8 is connected to the signal line 6. In the scanning drive unit 15, the on voltage and the off voltage supplied from the power supply circuit 15a via the wiring 15c are switched by the gate driver 15b and applied to the lines L1 to Lx of the scanning line 5. Yes. Then, each TFT 8 is turned on when an on-voltage is applied via the scanning line 5, discharges the charge accumulated in the radiation detection element 7 to the signal line 6, and also passes through the scanning line 5. When the off voltage is applied, the radiation state is turned off, the conduction between the radiation detection element 7 and the signal line 6 is interrupted, and the charge generated in the radiation detection element 7 is accumulated in the radiation detection element 7. It has become.

  A plurality of readout circuits 17 are provided in the readout IC 16, and the signal line 6 is connected to each readout circuit 17. In the reading process of the image data D, when the charge is released from the radiation detection element 7, the charge flows into the reading circuit 17 through the signal line 6, and the amplification circuit 18 corresponds to the amount of the charged charge. Output voltage value. Then, the correlated double sampling circuit (described as “CDS” in FIG. 3) 19 reads out the voltage value output from the amplifier circuit 18 as analog value image data D and outputs it to the downstream side. The output image data D is sequentially transmitted to the A / D converter 20 via the analog multiplexer 21, and is sequentially converted into digital image data D by the A / D converter 20, and is output to the storage means 23. Are stored sequentially.

  The control means 22 is a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, etc., not shown, connected to the bus, an FPGA (Field Programmable Gate Array), or the like. It is configured. It may be configured by a dedicated control circuit. The control means 22 is connected to a storage means 23 composed of SRAM (Static RAM), SDRAM (Synchronous DRAM), NAND flash memory or the like.

  The control unit 22 includes a power source 24 that supplies power necessary for each functional unit such as the scanning drive unit 15, the readout circuit 17, the storage unit 23, and the bias power source 14, and wireless communication with the outside via the antenna 41 and the connector 39. A communication unit 25 or the like for controlling communication in a system or a wired system is connected. Then, the control means 22 controls the operation of the scanning drive means 15 and the readout circuit 17 as described above during the reading process of the image data D, and the electric charges discharged from the radiation detection elements 7 are imaged. Data D is read out.

[Usage environment etc. of radiation imaging equipment]
Next, a usage environment in which the radiation image capturing apparatus 1 according to the present embodiment is used will be briefly described. As a usage environment in which the radiographic imaging device 1 is used, FIG. 4 illustrates a case where the radiographic imaging device 1 is used for imaging in a radiographing room, and in FIG. The case where it is brought into a hospital room or the like and photographing is performed is illustrated.

  As shown in FIG. 4, when the radiographic imaging device 1 is used for imaging in the imaging room Ra, the radiographic imaging device 1 is usually installed in a cassette holding portion (also referred to as a cassette holder) 51 a of the bucky device 51. Loaded. FIG. 4 shows a case where a bucky device 51A for standing position shooting and a bucky device 51B for standing position shooting are installed as the bucky device 51.

  The imaging room Ra is provided with at least one radiation irradiating device 52A for irradiating the radiation image capturing device 1 mounted on the bucky device 51 via a subject (not shown). In addition, in the photographing room Ra, a repeater provided with an access point 53 for relaying communication or the like between each device in the photographing room Ra, each device outside the photographing room Ra, etc. in a wireless method or a wired method. 54 is provided. The relay 54 is also connected to a generator 55 of the radiation irradiating device 52, a console 58 described later, and the like. The relay 54 is connected to the radiographic imaging device 1, the console 58, the generator 55 of the radiation irradiating device 52, and the like. The communication between the two and the transfer of the image data D are relayed.

  The front room (also referred to as an operation room or the like) Rb is provided with an operation console 57 of the radiation irradiating device 52, and an operator such as a radiation engineer operates the operation table 57 to emit radiation to the generator 55. An exposure switch 56 is provided for instructing the start of irradiation. The generator 55 performs various controls such as setting a tube current and an irradiation time for the radiation irradiation device 52 so that an appropriate dose of radiation is emitted from the radiation irradiation device 52.

  A console 58 formed of a computer or the like is provided in the front chamber Rb. Note that the console 58 may be configured to be provided outside the imaging room Ra or the front room Rb, in a separate room, or the like. The console 58 is provided with a display unit 58a configured to include a CRT (Cathode Ray Tube), an LCD (Liquid Crystal Display), or the like, and also includes an input unit 58b such as a mouse or a keyboard. In addition, the console 58 is connected to or has a built-in storage means 59 composed of an HDD (Hard Disk Drive) or the like.

  On the other hand, when the radiographic image capturing apparatus 1 is brought into the hospital room Rc or the patient's home or the like to perform imaging, the radiographic image capturing apparatus 1 is inserted between the bed B and the patient H as shown in FIG. Or applied to the body of the patient H. Further, when imaging is performed in the hospital room Rc or the like, as shown in FIG. 5, a so-called portable radiation irradiation device 52P or the like is brought into the hospital room Rc or the like, for example, by being mounted on the roundabout wheel 71 or the like.

  In this case, the repeater 54 provided with the access point 53 is built in the roundabout wheel 71, and the repeater 54 communicates between the generator 55 and the console 58 of the radiation irradiating device 52, and the radiation, as described above. The communication between the image capturing apparatus 1 and the console 58, the transfer of image data D, and the like are relayed. In FIG. 5, the input means 58b and the storage means 59 of the console 58 are not shown.

[Processing of the radiographic imaging device during radiography]
Here, the process of the radiographic imaging device 1 at the time of imaging will be described. When receiving a radiographing start signal from the console 58, the radiographic imaging device 1 starts a resetting process of the radiation detecting elements 7 for removing charges remaining in the radiation detecting elements 7 as preprocessing for imaging.

  For example, as shown in FIG. 6, the radiation detection element 7 is reset by sequentially applying an off voltage to the lines L <b> 1 to Lx of the scanning line 5 from the gate driver 15 b (see FIG. 3) of the scanning driving unit 15. Are sequentially turned on so that the charge remaining in the radiation detection element 7 is discharged to the signal line 6. The radiation detection element 7 is reset when, for example, a radiation engineer performs a first-stage operation (ie, a so-called half-press operation) on the exposure switch 56 of the radiation irradiation device 52. It is also possible to start the reset process as appropriate.

  Then, when a radiation engineer or the like performs a second-stage operation on the exposure switch 56 of the radiation irradiation device 52 (that is, a so-called full pressing operation), the generator 55 of the radiation irradiation device 52 sends an irradiation start signal to the radiation image capturing device 1. Send.

  When receiving the irradiation start signal, the control means 22 of the radiographic imaging apparatus 1 performs the reset process of the radiation detection element 7 performed at that time from the gate driver 15b to the last line of the scanning line 5 as shown in FIG. When the reset processing of the radiation detection element 7 for one frame is completed by applying to Lx, the gate driver 15b applies a turn-off voltage to each line L1 to Lx of the scanning line 5 to turn off each TFT8. To shift to the charge accumulation state.

  In addition, the control means 22 of the radiographic image capturing apparatus 1 transmits an interlock release signal to the radiation irradiation apparatus 52 side. Then, the generator 55 of the radiation irradiation device 52 causes the radiation irradiation device 52 to irradiate the radiation when the interlock release signal is received. A hatched portion in FIG. 6 represents a period during which radiation is irradiated from the radiation irradiation device 52.

  Then, as shown in FIG. 6, the control unit 22 of the radiographic imaging apparatus 1 continues the charge accumulation state for a predetermined time τ, and then applies an on-voltage to each of the lines L1 to Lx of the scanning line 5 from the gate driver 15b. The image data D is read out by sequentially applying the charges discharged from the radiation detection elements 7 as image data D by the readout circuit 17.

  Further, in the radiographic image capturing apparatus 1, after the image capturing, the offset data O is read out as shown in FIG. That is, the radiographic imaging device 1 repeats the same processing sequence as the processing sequence up to the readout processing of the image data D shown in FIG. 6 in a state where no radiation is irradiated (that is, performs the reset processing of the radiation detection element 7, After the charge accumulation state is continued for a predetermined time τ in a state where no radiation is irradiated, an ON voltage is sequentially applied from the gate driver 15b to each of the lines L1 to Lx of the scanning line 5), and the image data D is read out. In the same manner as described above, the offset data O is read out from the radiation detection elements 7 to read out the offset data O.

  Moreover, in the radiographic imaging device 1, after imaging | photography, the operation | movement which acquires the offset data O is performed as shown in FIG. That is, the radiographic imaging device 1 repeats the same processing sequence as the processing sequence up to the operation of acquiring the image data D shown in FIG. 6 in a state where no radiation is irradiated (that is, reset processing of the radiation detection element 7). After the charge accumulation state is continued for a predetermined time τ in a state where no radiation is irradiated, an ON voltage is sequentially applied from the gate driver 15b to each of the lines L1 to Lx of the scanning line 5). An operation for acquiring the offset data O is performed.

  In addition, as described above, there may be a case where imaging is performed while exchanging signals (that is, an irradiation start signal, an interlock release signal, etc.) between the radiation image capturing apparatus 1 and the radiation irradiation apparatus 52 side. Although there is no exchange of signals between the radiographic imaging device 1 and the radiation irradiating device 52 side, the radiographic imaging device 1 detects that radiation irradiation has been started and shifts to a charge accumulation state. In some cases, it is configured to perform shooting. In addition, about the structure in case the radiographic imaging apparatus 1 detects the irradiation start of radiation in this way, it is in detail in Unexamined-Japanese-Patent No. 2009-219538, international publication 2011/135917, international publication 2011/152093. Please refer to them.

  Even in such a configuration, the radiographic imaging device 1 repeats a processing sequence similar to the processing sequence of the operation for acquiring the image data D after imaging in the same manner as described above (note that radiation is not emitted). It is performed in a state where it is not irradiated.), An operation for obtaining the offset data O is performed.

Further, when the control unit 22 of the radiographic image capturing apparatus 1 reads the image data D and the offset data O as described above, the control unit 22 transfers the read image data D and offset data O to the console 50. The console 58 calculates so-called true image data D ^* by subtracting the offset data O from the image data D for each radiation detection element 7 in accordance with the following equation (1), and for the calculated true image data D ^*: Thus, a radiation image is generated by performing image processing such as gain correction, defective pixel correction, and gradation processing according to the imaging region.
D ^* = DO (1)

[About gain calibration necessity determination processing and notification processing]
Next, a configuration for determining whether or not gain calibration is necessary for the radiation image capturing apparatus 1 and a configuration for notification processing will be described. The operation of the radiographic image system 100 according to the present embodiment (the radiographic image capturing apparatus 1 when the radiographic image capturing apparatus 1 is configured to perform all processes as described above) will also be described.

[Assumptions]
In the present embodiment, the plurality of radiation detection elements 7 arranged in a two-dimensional shape of the radiation image capturing apparatus 1 are virtually divided into a plurality of regions. That is, as described above, a plurality of radiation detection elements 7 are two-dimensionally arranged on a sensor substrate (not shown) of the radiation image capturing apparatus 1 to form a detection unit P (see FIG. 3). As shown in FIG. 2, in this embodiment, the detection unit P (that is, a plurality of radiation detection elements 7, the same applies hereinafter) is virtually divided into a plurality of regions R1 to Rz.

  The size of R1 to Rz in each region is set to an appropriate size such as 100 × 100 pixels (that is, 100 × 100 radiation detection elements 7), for example. Note that the detection unit P is not actually physically divided into the plurality of regions R1 to Rz, but the detection unit P is considered to be divided into the plurality of regions R1 to Rz. Divided into two parts. Moreover, although the case where the detection part P is divided | segmented into each 8 * 10 area | region R1-Rz is shown in FIG. 8, this invention is not limited to the case where it divides | segments in that way.

  Further, as in the invention described in Patent Document 1 described above, each radiation detection element 7 (or each region R1 of the detection unit P as in the present embodiment) based on the image data D read out by the radiation imaging apparatus 1. When it is configured to calculate the exposure dose for each of Rz (when Rz), the image data D read out at the portion where the radiation has directly reached the radiation image capturing apparatus 1 (that is, the missing portion in the detection unit P) is saturated. Therefore, even if it is based on the image data D, it is not known how much radiation has actually been irradiated, and the exposure dose cannot be calculated accurately.

Therefore, in the present embodiment, the exposure dose is calculated using the offset data O, not the image data D. More precisely, as shown in FIG. 7, the offset data O read out after imaging for each radiation detection element 7 of the radiographic imaging device 1 is caused by the heat (temperature) of the radiation detection element 7. In addition to the offset o due to dark charges (also referred to as dark current or the like) constantly generated in the radiation detection element 7, a lag signal value Dlag due to the irradiation dose is included. That is, between the offset data O, the lag signal value Dlag, and the offset o due to the dark charge,
O = Dlag + o
∴Dlag = O-o (2)
There is a relationship.

  In the present embodiment, the case where the exposure dose is calculated based on the lag signal value Dlag will be described below. However, as described above, the offset data O includes the lag signal value Dlag, and the offset Even if the value of the data O is used as it is, the exposure dose can be calculated with sufficient accuracy. Therefore, in such a case, instead of subtracting the offset o due to the dark charge from the offset data O to calculate the lag signal value Dlag, the following processing is performed using the offset data O as it is. It is also possible to do. In this case, the lag signal value Dlag in the following description is read as offset data O.

  Here, the lag will be described. When the radiation image capturing apparatus 1 is irradiated with radiation, charges (that is, electron-hole pairs) are generated in each radiation detection element 7, and this is the image data D described above. In the reading process, the image data D is read out. At this time, the charge remaining in the radiation detection element 7 due to unread or the like is easily removed from the radiation detection element 7 by performing the reset process of the radiation detection element 7 described above. The However, it has been found that the lag generated by the radiation irradiation does not easily disappear from the radiation detection element 7 even if the reset process of the radiation detection element 7 is repeatedly performed.

  The reason why the lag does not disappear easily in this way is that some of the electrons and holes generated in the radiation detection element 7 due to the irradiation of radiation are changed to a kind of metastable state, and the radiation This is considered to be because the state of loss of mobility in the detection element is maintained for a relatively long time. And the electrons and holes in this metastable energy state are not always in the metastable energy level, but the energy level that is considered to be higher than the metastable energy little by little with thermal energy. Transition to the conduction band restores mobility. However, since the ratio is not necessarily large, it is considered that even if the reset process of each radiation detection element 7 is repeatedly performed, it does not easily disappear. There are still many unclear points about the mechanism of lag generation and persistence.

  As described above, since the generated lag does not disappear easily, the offset data O reading process (see FIG. 7) is performed immediately after the irradiation of radiation and the reading process of the image data D (see FIG. 6) is performed. Also read out from each radiation detection element 7. Therefore, as described above, the offset data O includes the signal value based on the lag, that is, the signal value Dlag of the lag.

  On the other hand, in the study by the present inventors, the dose d of the radiation applied to the radiation detection element 7 during imaging, that is, the exposure dose d of the radiation detection element 7, and the signal value Dlag of the lag calculated according to the above equation (2) Is known to have a monotonically increasing relationship as shown in FIG. 9, for example. In this case, even when the radiation detection element 7 is irradiated with a dose of radiation equal to or higher than the dose dlimit corresponding to the value when the image data D is saturated, the lag signal is increased when the radiation dose d of the radiation detection element 7 increases. The value Dlag also increases.

  For this reason, in the present embodiment, even when the radiation detection element 7 is irradiated with a radiation dose equal to or higher than the exposure dose dlimit that saturates the image data D, the lag signal can be obtained by referring to the relationship shown in FIG. Based on the value Dlag, the exposure dose of the radiation detection element 7 can be accurately calculated.

  In order to calculate the lag signal value Dlag according to the above equation (2), in addition to the offset data O read for each radiation detection element 7 at the time of imaging, the offset o due to the dark charge for each radiation detection element 7 is calculated. Data is needed. The offset o due to the dark charge is always generated in the radiation detection element 7 due to the heat (temperature) of the radiation detection element 7 as described above, regardless of the lag generated during imaging as described above. This is an offset o due to dark charge.

  Therefore, for example, when the radiation image capturing apparatus 1 is shipped from the factory, the processing sequence up to, for example, the offset data O reading process illustrated in FIG. 7 is performed in a state where the radiation image capturing apparatus 1 is not irradiated with radiation. The offset o due to the charge can be read in advance. Further, instead of reading out the offset o due to the dark charge in advance in this way, for example, every time photographing is performed, or on the day when photographing is performed using the radiographic image capturing apparatus 1, darkness is performed in advance (that is, before photographing). It is also possible to read the offset o due to the charge.

[Basic configuration of the present invention]
In the present invention, basically, for each region R1 to Rz obtained by virtually dividing the detection unit P (that is, the plurality of radiation detection elements 7) of the radiographic image capturing apparatus 1 as described above, The exposure dose d is calculated based on the signal value Dlag of the lag, and the cumulative exposure dose is updated by integrating the exposure dose d for each of the regions R1 to Rz. At the same time, the absolute value of the difference between the cumulative exposure doses of the regions (for example, adjacent regions) is calculated, and the absolute value of the difference equal to or larger than the set threshold exists in the calculated absolute value of the difference. When the absolute value of such a difference is determined to be present, the radiographic imaging apparatus 1 is configured to notify the user of prompting execution of gain calibration.

[Examples]
Hereinafter, the above-described configuration of the present invention will be specifically described with reference to one embodiment. In this embodiment, as shown in FIGS. 10A and 10B, the radiographic image capturing system 100 includes a radiographic image capturing apparatus 1 and a computer other than the radiographic image capturing apparatus 1. In the following, the case where the computer is the console 58 described above will be described, but a computer other than the console 58 may be used.

  In this embodiment, the radiographic imaging device 1 performs processing such as calculating the exposure dose d for each of the regions R1 to Rz and updating the cumulative exposure dose, and the like, and the console 58 (that is, the radiographic imaging device 1). A computer other than the above, the same shall apply hereinafter) will be described.

  As shown in FIG. 10B, the console 58 includes a CPU 58A, a ROM 58B, a memory 58C including a RAM, an input / output interface 58D, and the like connected by a bus 58E. Further, when the storage means 59 constituted by the above-described HDD (Hard Disk Drive) or the like is connected to or built in the console 58, these are also included in the memory 50c. Further, FIG. 10A shows a case where the radiographic imaging apparatus 1 and the console 58 transmit and receive signals and the like in a wireless manner, but communication is performed in a wired manner via a cable and the like (not shown). It is also possible to configure.

  When the control means 22 (see FIG. 3) of the radiographic image capturing apparatus 1 performs the offset data O reading process as described above after the capturing (see FIG. 7), the image data D and the offset data O as described above. Is transferred to the console 58, and the offset o due to the dark charge read in advance at the time of shipment from the factory or before photographing as described above is read from the memory such as the storage means 23, and the calculation of the above equation (2) is performed. The lag signal value Dlag is calculated for each radiation detection element 7.

  And the control means 22 is the lag of the radiation detection element 7 which belongs to the said area | region Rn for every area | region R1-Rz (refer FIG. 8; hereafter, area | region R1-Rz is generally represented as area | region Rn) of the detection part P. The statistical value Dlag_st of the signal value Dlag is calculated. In this case, the statistical value Dlag_st of the lag signal value Dlag can be calculated, for example, as an average value, a total value, an intermediate value, or the like of the lag signal value Dlag of the radiation detection element 7 belonging to the region Rn.

  Based on the calculated lag signal value Dlag statistical value Dlag_st for each region Rn, the control means 22 stores the exposure dose d of the radiation detection element 7 stored in the storage means 23 or written in the program. And a lag signal value Dlag (see FIG. 9), the statistical value dst of the exposure dose d in the region Rn is calculated. The statistical value dst of the exposure dose d means an exposure dose corresponding to the statistical value Dlag_st of the lag signal value Dlag.

  Then, the control means 22 calculates, for each region Rn, the calculated statistical value dst of the exposure dose d, the integrated value of the statistical value dst of the exposure dose d calculated in the past (that is, the calculation calculated at each imaging until the previous imaging). The cumulative exposure dose Σdst for each region Rn is updated by adding to the cumulative exposure dose Σdst that is the integrated value of the statistical value dst of the exposure dose d in the region Rn.

  The control means 22 of the radiographic image capturing apparatus 1 performs the calculation process of the statistical value dst of the exposure dose d and the update process of the cumulative exposure dose Σdst for each region Rn (that is, each region R1 to Rz) of the detection unit P. Do each. Then, the control means 22 overwrites and stores the cumulative exposure dose Σdst updated in this way in the storage means 23 (see FIG. 3) for each region Rn. In the present embodiment, the accumulated exposure dose Σdst of each region Rn is updated as described above for each radiographing.

  As described above, in the present embodiment, the control unit 22 of the radiographic image capturing apparatus 1 functions as an update unit that updates the cumulative exposure dose Σdst for each region Rn of the detection unit P, and the storage unit 23 of the radiographic image capturing apparatus 1. However, it functions as a storage means for storing the cumulative exposure dose Σdst for each updated region Rn.

  On the other hand, in this embodiment, the control means 22 of the radiographic image capturing apparatus 1 is a material for determining whether the console 58 needs to perform gain calibration of the radiographic image capturing apparatus 1 as described above. The absolute value | ΔΣdst | of the difference ΔΣdst of the cumulative exposure dose Σdst between the regions Rn is calculated.

  Specifically, when the control unit 22 of the radiographic image capturing apparatus 1 updates the accumulated exposure dose Σdst for each region Rn of the detection unit P and stores it in the storage unit 23 as described above, the accumulation of the regions Rn is accumulated. The absolute value | ΔΣdst | of the difference ΔΣdst of the exposure dose Σdst is calculated. That is, in the present embodiment, the control means 22 of the radiographic imaging apparatus 1 has the absolute value of the difference between the accumulated dose Σdst in the region Rn and the accumulated dose Σdst in the other region Rn in the region Rn of the detection unit P. It functions as a calculating means for calculating | ΔΣdst |.

  At that time, the absolute value | ΔΣdst | of the difference ΔΣdst of the cumulative exposure dose Σdst may be calculated for a certain region Rn with respect to all other regions.

  Further, as described above, when a part of the scintillator 3 of the radiographic image capturing apparatus 1 is more deteriorated and has a lower sensitivity than the other part, image unevenness is visually recognized in the radiation image due to the sensitivity unevenness of the scintillator 3. It may become a state that. Such image unevenness is clearer when there is sensitivity unevenness between adjacent parts on the scintillator 3 than when there is sensitivity unevenness between parts far apart on the scintillator 3. It becomes visible.

  Therefore, in this embodiment, for each region Rn, the control unit 22 determines the absolute value | ΔΣdst of the difference ΔΣdst between the cumulative dose Σdst in the region Rn and the cumulative dose Σdst in other regions adjacent to the region Rn. | Is calculated. That is, for example, in the case of each of the regions R1 to Rz shown in FIG. 8, in each region Rn at the four corners of the detection unit P, between the three adjacent regions Rn, in each region Rn on the side of the detection unit P The absolute value | ΔΣdst | of the difference ΔΣdst is calculated between the five adjacent regions Rn and between the eight regions Rn adjacent to each other region Rn of the detection unit P. Can be configured.

  On the other hand, in this embodiment, the CPU 58A (see FIG. 10B) of the console 58 has the absolute value | ΔΣdst | of the difference ΔΣdst between the regions Rn calculated by the control means 22 of the radiographic imaging apparatus 1 as described above. Is determined to determine whether or not the absolute value | ΔΣdst | of the difference ΔΣdst equal to or greater than the set threshold ΔΣdth exists, and the difference ΔΣdst greater than or equal to the threshold ΔΣdth is included in the absolute value | ΔΣdst | When it is determined that there is an absolute value | ΔΣdst |, there is a notification process that prompts the radiographic imaging apparatus 1 to execute gain calibration.

  That is, in this embodiment, the CPU 58a of the console 58 (that is, the CPU of the computer) functions as a determination unit and a notification unit that perform the above-described determination process and notification process. As a method of notification, for example, it is possible to display characters or the like on the display unit 58a of the console 58, or to generate sound from a speaker (not shown). It is also possible to make a configuration such that the display device, the sound generation device, or the like is notified by transmitting a signal from the console 58 to a separate display device, a sound generation device, or the like.

  The absolute value of the difference ΔΣdst between the regions Rn of the cumulative exposure dose Σdst updated for each region Rn obtained by virtually dividing the detection unit P (ie, the plurality of radiation detection elements 7) of the radiographic imaging apparatus 1 into a plurality of regions Rn | When ΔΣdst | is equal to or greater than the threshold value ΔΣdth, there is a possibility that sensitivity unevenness occurs between the regions Rn of the detection unit P, that is, between the corresponding portions of the scintillator 3 corresponding thereto. In such a case, if radiography is performed using the radiographic image capturing apparatus 1 as it is, image nonuniformity due to the sensitivity nonuniformity of the scintillator 3 may be visually recognized in the radiographic image captured. There is sex.

  However, according to the present invention, in such a case, the determination means (the CPU 58A of the console 58 in the above embodiment) sets the absolute value | ΔΣdst | of the difference ΔΣdst between the regions Rn. The absolute value | ΔΣdst | of the difference ΔΣdst greater than or equal to the threshold ΔΣdth is accurately determined, and the notifying means (CPU 58A of the console 58 in the above embodiment) prompts the radiographic imaging apparatus 1 to perform gain calibration. Notification is performed accurately.

[effect]
As described above, according to the radiographic image capturing system 100 according to the present invention (when the radiographic image capturing apparatus 1 is configured to perform all processing as described above, the radiographic image capturing apparatus 1). When the sensitivity unevenness occurs in the scintillator 3 due to the cumulative exposure dose of the radiation irradiated to 1 or when there is a possibility that the sensitivity unevenness has occurred, it is accurately recognized and the gain of the radiation image capturing apparatus 1 is gained. It is possible to accurately perform notification for urging to perform calibration.

  Therefore, the user who has received such notification performs the gain calibration by himself, calls a service person to perform the gain calibration, or sends the radiographic image capturing apparatus 1 to the manufacturer. Since gain calibration can be accurately performed on the imaging apparatus 1, image unevenness due to sensitivity unevenness of the scintillator 3 is visually recognized in the radiographic image captured using the radiographic image capturing apparatus 1. It is possible to accurately prevent the situation from occurring.

  Further, according to the radiographic image capturing system 100 (or the radiographic image capturing apparatus 1) according to the present invention, the difference ΔΣdst that is equal to or larger than the set threshold ΔΣdth in the absolute value | ΔΣdst | of the difference ΔΣdst between the regions Rn. Since it is only necessary to perform gain calibration for the radiographic image capturing apparatus 1 only when it is determined that there is an absolute value | ΔΣdst |, there is no need to periodically perform gain calibration of the radiographic image capturing apparatus 1.

  Furthermore, according to the radiographic image capturing system 100 (or the radiographic image capturing apparatus 1) according to the present invention, as described above, it is possible to determine the necessity of gain calibration using the offset data O read at the time of capturing. Therefore, unlike the prior art, it is not necessary to perform operations such as irradiating the radiation image capturing apparatus 1 with radiation in order to determine whether or not the gain calibration of the radiation image capturing apparatus 1 is necessary.

  Note that each region Rn in the present embodiment can be configured to be set for each pixel (that is, each radiation detection element 7), but image unevenness on the radiation image due to sensitivity unevenness of the scintillator 3 is When the pixel ranges (ranges of several tens to several hundreds of pixels) wider than the pixel ranges occupied by the individual radiation detection elements 7 are compared, they appear as shading. Therefore, as in the present embodiment, instead of each radiation detection element 7 of the radiographic imaging device 1, the cumulative exposure dose is calculated for each region Rn in which the detection unit P (that is, a plurality of radiation detection elements 7) is virtually divided. By calculating and comparing the cumulative exposure dose for each region Rn (that is, the sensitivity for each region Rn), it is determined whether or not the image unevenness is visually recognized on the radiation image due to the sensitivity unevenness of the scintillator 3. It becomes possible to judge more accurately.

  Therefore, in order to determine whether or not the image unevenness is visually recognized on the radiographic image, that is, whether or not the sensitivity unevenness occurs in the scintillator 3, the radiographic image capturing apparatus 1 as in the present embodiment. It is preferable to calculate the cumulative exposure dose Σdst for each region Rn obtained by virtually dividing the detection unit P (that is, the plurality of radiation detection elements 7). Then, the size, shape, and the like of each region Rn are set to an appropriate size, shape, and the like that can accurately determine whether or not sensitivity unevenness occurs in the scintillator 3.

  Further, when the radiation dose d is calculated for each radiation detection element 7 and the cumulative radiation dose Σd is updated, the cumulative radiation dose Σd for one image (several thousand × several thousands) is stored in the storage unit 23. However, if the cumulative exposure dose Σdst for each region Rn is updated as in the present embodiment, for example, 8 × 10 = 80 as shown in FIG. It is only necessary to store a smaller number of accumulated doses Σdst. Therefore, there is a merit that it becomes possible to remarkably reduce the stored amount of accumulated exposure dose.

[Modification 1]
As described above, once generated, the lag does not easily disappear from the radiation detection element 7, but as shown in FIG. 11, immediately after the lag is generated (see t = 0 in FIG. 11). That is, immediately after the radiation image capturing apparatus 1 is irradiated with radiation, the generated amount dQ per unit time in the radiation detection element 7 is the largest, and the generated amount dQ per unit time decreases as time elapses. To go.

  The time from when the radiation image capturing apparatus 1 is irradiated with radiation (see the hatched portion in FIG. 6) until the offset data O (see FIG. 7) is read is from the gate driver 15b of the scanning drive unit 15 to the scanning line. As can be seen from the fact that the on-voltage is sequentially applied to each of the five lines L1 to Lx and the reading process of the offset data O is performed, the line is different for each line L1 to Lx of the scanning line 5.

  The longer the time from when the radiation image capturing apparatus 1 is irradiated with radiation until the offset data O is read out, the more charge due to the lag is accumulated in the radiation detection element 7. Therefore, even when the radiation detection element 7 is irradiated with the same dose of radiation (exactly, the irradiated radiation is converted into electromagnetic waves by the scintillator 3, and the amount of electromagnetic waves irradiated to the radiation detection elements 7 is the same. Even if the timing at which the offset data O is read out after irradiation is delayed, the lag component included in the read offset data O, that is, the lag signal calculated by the above equation (2) The value Dlag increases.

  Therefore, the time from when the radiation image capturing apparatus 1 is irradiated with radiation until the offset data O is read is calculated for each of the lines L1 to Lx of the scanning line 5, and the read offset data O or lag signal is read out. It is also possible to configure so that the value Dlag is corrected according to the calculated time.

[Modification 2]
In the above-described embodiment, the radiographic imaging apparatus 1 performs processing such as calculating the exposure dose d for each of the regions R1 to Rz and updating the cumulative exposure dose, and the console 58 (that is, the radiographic imaging apparatus). The case where it was comprised so that said judgment process and alerting | reporting process may be performed by computer other than 1) was demonstrated.

  However, as described above, the radiation image capturing apparatus 1 may be configured to perform all the processes up to the notification process. In this case, needless to say, the control unit 22 of the radiographic image capturing apparatus 1 functions as an update unit, a calculation unit, a determination unit, a determination unit, and a notification unit, and the storage unit 23 of the radiographic image capturing apparatus 1 is updated. It functions as a storage unit that stores the cumulative exposure dose Σdst for each region Rn.

  The radiographic imaging apparatus 1 may perform the above determination process, and only the notification process may be performed by a computer other than the radiographic imaging apparatus 1 such as the console 58. In this case, the control unit 22 of the radiographic image capturing apparatus 1 functions as an update unit, a calculation unit, a determination unit, and a determination unit, the storage unit 23 of the radiographic image capturing apparatus 1 functions as a storage unit, and the CPU 58A of the console 58. Functions as a notification means.

  Further, as described above, the image data D and the offset data O are transferred from the radiographic image capturing apparatus 1 to the console 58 for each radiographing. Therefore, the radiographic image capturing apparatus 1 can be configured to perform only the process of reading the offset data O and transferring it to the console 58 and perform other processes by a computer such as the console 58. In this case, the CPU 58A of the console 58 functions as update means, calculation means, determination means, determination means, and notification means, and the memory 58C of the console 58 functions as storage means.

  As described above, it is possible to appropriately determine which device is configured to have the functions as the update unit, the storage unit, the calculation unit, the determination unit, and the notification unit in the present invention.

[Modification 3]
In the above embodiment, the control means 22 of the radiographic image capturing apparatus 1 uses the console 58 (that is, the radiographic image capturing apparatus) to calculate the absolute values | ΔΣdst | of all the differences ΔΣdst calculated for all the regions Rn of the detection unit P. The computer 58A of the console 58 transmits the absolute value | ΔΣdst | of the difference ΔΣdst to the absolute value | ΔΣdst | of the difference ΔΣdst that is equal to or greater than the set threshold ΔΣdth. The description has been made on the assumption that a determination process for determining whether or not to perform the determination is performed.

  However, as described above, it is not necessary to determine whether or not the absolute value | ΔΣdst | of all the differences ΔΣdst | is greater than or equal to the threshold value ΔΣdth, and the maximum value | ΔΣdst | max of the absolute value | ΔΣdst | If so, at least one of the calculated absolute values | ΔΣdst | of the differences ΔΣdst | has an absolute value | ΔΣdst | of the difference ΔΣdst equal to or greater than the threshold ΔΣdth.

  For example, the control means 22 of the radiographic imaging apparatus 1 extracts the maximum value | ΔΣdst | max from the absolute values | ΔΣdst | of all the differences ΔΣdst calculated for each region Rn as described above, and the maximum Only the value | ΔΣdst | max is transmitted to the console 58, and the CPU 58A of the console 58 is configured to determine whether or not the transmitted maximum value | ΔΣdst | max is equal to or larger than a set threshold value ΔΣdth. Is possible.

  If comprised in this way, the control means 22 of the radiographic imaging device 1 will calculate the absolute value | ΔΣdst | of the difference ΔΣdst of the cumulative exposure dose Σdst between the regions Rn of the detection unit P every time the absolute value | ΔΣdst | By comparing the magnitudes of | ΔΣdst | and leaving the absolute value | ΔΣdst | of the larger difference ΔΣdst |, the maximum value | ΔΣdst | max of the absolute value | ΔΣdst | of the difference ΔΣdst can be easily extracted. Further, the data to be transmitted from the radiographic imaging apparatus 1 to the console 58 is only one of the maximum values | ΔΣdst | max, and the CPU 58A of the console 58 further transmits the maximum value | ΔΣdst | max and the threshold value ΔΣdth. Therefore, the necessity of gain calibration can be accurately determined in a short time.

[Modification 4]
As described above, the control unit 22 of the radiographic imaging apparatus 1 is configured to calculate the absolute value | ΔΣdst | of the difference ΔΣdst or extract the maximum value | ΔΣdst | max from them. In this case, the absolute value | ΔΣdst | and the maximum value | ΔΣdst | max of the calculated difference ΔΣdst may be transmitted, for example, for each photographing.

  Further, when imaging is performed, a signal may be transmitted from the console 58 to the radiographic image capturing apparatus 1 to activate or wake up the radiographic image capturing apparatus 1. The transmission request is transmitted to the image capturing apparatus 1, and the absolute value | ΔΣdst | of the difference ΔΣdst or the maximum value | ΔΣdst | max that the radiation image capturing apparatus 1 calculates or extracts in accordance with the transmission request is displayed on the console 58. It is also possible to configure to transmit to.

[Modification 5]
On the other hand, for example, as shown in FIG. 8, the above-described processes are performed on each region Rn obtained by virtually dividing the detection unit P (a plurality of radiation detection elements 7) of the radiographic image capturing apparatus 1. As shown, each of the above-described processes can also be performed for each region Rn ^{* obtained} by virtually dividing the detection unit P by changing the way of division.

In FIG. 12, the size, shape, and the like of the region Rn ^* are basically not changed from those of the region Rn in FIG. 8, and the virtual division method of the detection unit P of the radiographic image capturing apparatus 1 shown in FIG. In this case, the detection unit P is virtually divided in such a manner as to be shifted. In addition to this, the size, shape, etc. of each region Rn ^* that virtually divides the detection unit P is changed within the allowable range from the size, shape, etc. of the region Rn shown in FIG. It is also possible to change the way of virtually dividing the detection unit P.

Then, in this way, each of the above-described processes for each region Rn (for example, see FIG. 8) obtained by virtually dividing the detection unit P, and each of the detection unit P that is virtually divided by another method If the process for performing each of the above-described processes for the region Rn ^* (see, for example, FIG. 12) is performed in parallel, the determination means (the CPU 58A of the console 58 or the control means 22 of the radiographic imaging apparatus 1) can be used. On the other hand, in one process, it is impossible to determine that gain calibration is necessary (that is, the absolute value of the difference ΔΣdst | is greater than the threshold ΔΣdth in the absolute value | ΔΣdst | of the calculated difference ΔΣdst |). However, in the other process, it may be determined that gain calibration is necessary.

  Therefore, by configuring as described above, in a state that does not depend on the virtual division method of the detection unit P of the radiation image capturing apparatus 1 (or in a state where the dependence on the virtual division method is weakened). Thus, the determination means can accurately determine whether or not the gain calibration is necessary (that is, whether or not the absolute value of the difference ΔΣdst | is greater than the threshold ΔΣdth in the absolute value | ΔΣdst | of the calculated difference ΔΣdst |). .

[Modification 6]
In the present embodiment, as described above, the absolute value | ΔΣdst | of the difference greater than or equal to the threshold ΔΣdth exists in the absolute value | ΔΣdst | of the difference ΔΣdst of the cumulative exposure dose Σdst between the regions Rn of the detection unit P. In this case, the case has been described in which the radiographic imaging device 1 is configured to perform notification that prompts execution of gain calibration when it is determined.

  However, instead of calculating the cumulative exposure dose Σdst and determining the necessity of gain calibration of the radiographic imaging device 1 based on the difference ΔΣdst in this way, for example, each of the detection units P Differences in the statistical values of the exposure dose between the regions Rn are accumulated, and when the absolute value becomes equal to or greater than the threshold value, the radiographic imaging apparatus 1 is configured to notify the user that the gain calibration is performed. It is also possible.

  In other words, the calculation means calculates the statistical value of the lag signal value Dlag (or the offset data O as described above, the same applies below) due to the irradiation dose for each region Rn of the detection unit P of the radiographic imaging device 1. Dlag_st is calculated, and the statistical value dst of the exposure dose d in the region Rn is calculated based on the statistical value Dlag_st of the lag signal value Dlag for each region Rn.

  Then, the update means calculates the difference in the statistical value dst of the dose d between the regions Rn, and calculates the statistical value st of the dose d between the calculated regions Rn, not the difference ΔΣdst of the cumulative dose Σdst as described above. Is added to the accumulated value ΣΔdst of the difference Δdst of the statistical value dst of the exposure dose d between the regions Rn calculated in the past, and the cumulative value ΣΔdst of the difference Δdst of the statistical value dst of the exposure dose d between the regions Rn Update. The storage unit stores the cumulative value ΣΔdst of the difference Δdst of the statistical value dst of the exposure dose d between the updated regions Rn.

  Then, the determination means determines whether the cumulative value ΣΔdst of the difference Δdst whose absolute value is equal to or larger than the set threshold value ΣΔdth exists in the cumulative value ΣΔdst of the difference Δdst of the statistical value dst of the exposure dose d between the regions Rn. When the determination means determines that the accumulated value ΣΔdst of the difference Δdst whose absolute value is equal to or greater than the threshold ΣΔdth is present in the accumulated value ΣΔdst of the difference Δdst, the radiographic image is determined. The imaging apparatus 1 can be configured to perform notification that prompts execution of gain calibration.

  The scintillator is also used when the difference in the statistical value dst of the exposure dose d between the regions Rn of the detection unit P of the radiographic imaging apparatus 1 is accumulated and the absolute value of the accumulated value ΣΔdst is equal to or greater than a predetermined value (that is, the threshold ΣΔdth or greater). 3 may cause sensitivity unevenness. However, if configured as described above, even in such a case, it is accurately recognized and prompts the radiographic imaging apparatus 1 to perform gain calibration. Notification can be performed accurately.

[Modification 7]
By the way, as described above, when there is sensitivity unevenness between adjacent parts on the scintillator 3 of the radiographic image capturing apparatus 1, the image unevenness is visible in the radiographic image due to the sensitivity unevenness of the scintillator 3. For example, since there is little sensitivity unevenness between adjacent parts on the scintillator 3, such image unevenness does not occur, but there are cases where the overall gradation changes to a gradation.

  That is, when the scintillator 3 has sensitivity unevenness and the radiation image capturing apparatus is uniformly irradiated with radiation without capturing the subject, and the radiation image is captured, for example, as shown in FIG. In some cases, shading appears on the image p in a gradation. In FIG. 13, the shading is emphasized. Further, even when the radiation image capturing apparatus is uniformly irradiated and imaged, for example, the center part of the radiation image p may be captured brightly and the peripheral part may be captured darkly.

  In such a case, since the shade between adjacent portions of the radiographic image p does not change greatly, it is not visually recognized as image unevenness, but a portion of the radiographic image p looks darker than other portions, The radiation image p may be difficult to see.

  Therefore, for example, in parallel with each process according to the present invention described above, the maximum value is calculated from the cumulative exposure doses Σdst for each region Rn of the detection unit P calculated and updated as described above. And extracting the minimum value and calculating the difference between them, or calculating the average value of the cumulative exposure dose Σdst for each region Rn and comparing the average value with the maximum and minimum values, When the difference between the maximum value and the minimum value is larger than a predetermined threshold value, or when the difference between the maximum value and the average value or the difference between the average value and the minimum value is larger than a predetermined threshold value, each of the scintillators 3 It is determined that there is a relatively large sensitivity unevenness in the portion, and there is a possibility that the gradation appears on the radiographic image p in a gradation, so that the radiographic imaging apparatus 1 is notified to urge execution of gain calibration. Configure It is possible.

  With this configuration, relatively large sensitivity unevenness occurs in each part of the scintillator 3, and the gain of the radiographic image capturing apparatus 1 can be obtained when there is a possibility that the gradation appears on the radiographic image p in a gradation. By executing calibration, it is possible to accurately prevent gradations from appearing in a gradation on the radiation image p due to uneven sensitivity of each part of the scintillator 3.

  Needless to say, the present invention is not limited to the above-described embodiments and the like, and can be appropriately changed without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Radiation imaging device 3 Scintillator 7 Radiation detection element 22 Control means (update means, calculation means, judgment means, notification means)
23 storage means 58 console (computer)
58A CPU (update means, calculation means, judgment means, notification means)
58C memory (storage means)
100 Radiation imaging system d Exposure dose Dlag Lag signal value Dlag_st Lag signal value statistical value dst Exposure dose statistical value Rn Region | ΔΣdst | Difference absolute value | ΔΣdst | max Maximum absolute difference value ΔΣdth threshold Σdst Cumulative dose ΣΔdst Cumulative value ΣΔdth threshold

Claims (9)

A radiographic imaging apparatus comprising a scintillator and a plurality of radiation detection elements arranged two-dimensionally;
In a state where radiation is not irradiated after imaging by the radiographic imaging device for each of the regions when the plurality of the radiation detection elements arranged in a two-dimensional array of the radiographic imaging device are virtually divided into a plurality of regions. The statistical value of the signal value of the lag caused by the irradiation dose obtained for each of the radiation detection elements is calculated, and the statistical value of the exposure dose in the region based on the statistical value of the signal value of the lag for each of the calculated regions A value is calculated, and for each region, the calculated statistical value of the radiation dose is added to a cumulative radiation dose that is an integrated value of statistical values of the radiation dose calculated in the past, and a cumulative radiation dose for each region is calculated. Updating means for updating
Storage means for storing the cumulative exposure dose for each of the updated areas;
A calculating means for calculating an absolute value of a difference between the accumulated doses between the regions;
A judging means for judging whether or not an absolute value of a difference equal to or larger than a set threshold exists in the calculated absolute value of the difference;
An informing means for informing the radiographic imaging apparatus to execute gain calibration when the determining means determines that the absolute value of the difference equal to or greater than the threshold is present in the absolute value of the difference;
A radiographic imaging system comprising:   The update means calculates a statistical value of offset data acquired for each of the radiation detection elements in a state in which radiation is not irradiated after imaging by the radiographic image capturing apparatus, instead of the statistical value of the lag, and the calculated area The statistical value of the exposure dose in the region is calculated based on the statistical value of the offset data for each region, and the calculated statistical value of the exposure dose for each region is integrated with the statistical value of the exposure dose calculated in the past. The radiation image capturing system according to claim 1, wherein the cumulative exposure dose for each region is updated by adding to the cumulative exposure dose that is a value.   The said calculation means calculates the absolute value of the difference of the said cumulative exposure dose in the said area | region and the said cumulative exposure dose in the said other area | region adjacent to the said area | region for every said area | region. Or the radiographic imaging system of Claim 2. The update means, the storage means, and the calculation means are provided in the radiographic imaging device,
The determination means and the notification means are provided in a computer other than the radiographic imaging device,
The calculation means of the radiographic image capturing apparatus extracts the maximum value from the absolute value of the difference calculated for each region and transmits it to the computer,
The radiographic imaging system according to claim 1, wherein the determination unit of the computer performs processing based on an absolute value of the transmitted difference. A radiographic imaging apparatus comprising a scintillator and a plurality of radiation detection elements arranged two-dimensionally;
In a state where radiation is not irradiated after imaging by the radiographic imaging device for each of the regions when the plurality of the radiation detection elements arranged in a two-dimensional array of the radiographic imaging device are virtually divided into a plurality of regions. The statistical value of the signal value of the lag caused by the irradiation dose obtained for each of the radiation detection elements is calculated, and the statistical value of the exposure dose in the region based on the statistical value of the signal value of the lag for each of the calculated regions A calculating means for calculating a value;
The difference in the statistical value of the exposure dose between the areas is calculated, and the difference in the statistical value of the exposure dose between the calculated areas is set to the cumulative value of the difference in the statistical value of the exposure dose between the areas calculated in the past. In addition, update means for updating the cumulative value of the difference in the statistical value of the exposure dose between the regions,
Storage means for storing a cumulative value of a difference in statistical values of exposure dose between the updated areas;
In the cumulative value of the difference between the statistical values of the exposure dose between the regions, a determination means for determining whether or not the absolute value of the cumulative value of the difference equal to or more than a set threshold exists,
When the determination means determines that a cumulative value of a difference whose absolute value is greater than or equal to the threshold value is present in the cumulative value of the difference, a notification that prompts execution of gain calibration for the radiographic imaging device Notification means to perform;
A radiographic imaging system comprising:   The calculation means calculates a statistical value of offset data acquired for each of the radiation detection elements in a state in which no radiation is irradiated after imaging by the radiographic imaging device, instead of the statistical value of the lag, and the calculated area The radiation image capturing system according to claim 5, wherein a statistical value of an exposure dose in the region is calculated based on a statistical value of the offset data for each. The update means, the storage means, and the calculation means are provided in the radiographic imaging device,
The radiographic imaging system according to claim 1, wherein the determination unit and the notification unit are provided in a computer other than the radiographic imaging device. In a radiographic imaging apparatus including a scintillator and a plurality of radiation detection elements arranged in a two-dimensional shape,
Irradiation dose acquired for each of the radiation detection elements in a state in which radiation is not irradiated after imaging for each of the regions when the plurality of radiation detection elements arranged in a two-dimensional manner are virtually divided into a plurality of regions. Calculate the statistical value of the lag signal value due to the above, calculate the statistical value of the exposure dose in the region based on the calculated statistical value of the lag signal value for each region, and calculate for each region Updating means for adding the statistical value of the exposure dose to the cumulative exposure dose that is an integrated value of the statistical values of the exposure dose calculated in the past, and updating the cumulative exposure dose for each region;
Storage means for storing the cumulative exposure dose for each of the updated areas;
A calculating means for calculating an absolute value of a difference between the accumulated doses between the regions;
A judging means for judging whether or not an absolute value of a difference equal to or larger than a set threshold exists in the calculated absolute value of the difference;
An informing means for informing the execution of gain calibration when the determining means determines that the absolute value of the difference equal to or greater than the threshold exists in the absolute value of the difference;
A radiographic imaging apparatus comprising: In a radiographic imaging apparatus including a scintillator and a plurality of radiation detection elements arranged in a two-dimensional shape,
Irradiation dose acquired for each of the radiation detection elements in a state in which radiation is not irradiated after imaging for each of the regions when the plurality of radiation detection elements arranged in a two-dimensional manner are virtually divided into a plurality of regions. Calculating a statistic value of the signal value of the lag caused by the calculation, and calculating a statistical value of the exposure dose in the region based on the calculated statistical value of the signal value of the lag for each region,
The difference in the statistical value of the exposure dose between the areas is calculated, and the difference in the statistical value of the exposure dose between the calculated areas is set to the cumulative value of the difference in the statistical value of the exposure dose between the areas calculated in the past. In addition, update means for updating the cumulative value of the difference in the statistical value of the exposure dose between the regions,
Storage means for storing a cumulative value of a difference in statistical values of exposure dose between the updated areas;
In the cumulative value of the difference between the statistical values of the exposure dose between the regions, a determination means for determining whether or not the absolute value of the cumulative value of the difference equal to or more than a set threshold exists,
Informing means for informing the execution of gain calibration when the judging means judges that the accumulated value of the difference includes the accumulated value of the difference whose absolute value is equal to or greater than the threshold value;
A radiographic imaging apparatus comprising:

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