JP2001276029A - Photographing instrument, its system, its control method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photographing instrument by which a photographing image with optimum high quality for medical diagnosis by a configuration for preventing image quality deterioration by the influence of an electromagnetic noise and a vibration caused by grid movement. SOLUTION: A control means 111 receives a radiation transmitted from a subject 102 by an imaging element 106 via a movable grid 104, the movement driving of the grid 104 is stopped after the end of the emission of the radiation to the subject 102 as operation control when the storing signal of the imaging element 106 is read, the movement driving is stopped and, then, the reading of the storing signal of the imaging element 106 is started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiographing apparatus, a radiographing system, a radiographing control method, and the like, which are used, for example, in an apparatus or a system for radiographing an object using a grid.
The present invention relates to a storage medium storing computer-readable processing steps for executing the same.

[0002]

2. Description of the Related Art Conventionally, a radiation method of irradiating an object with radiation such as X-rays, detecting the intensity distribution of the radiation transmitted through the object, and acquiring a radiation image of the object has been known for industrial use. It is widely and generally used in fields such as nondestructive testing and medical diagnosis.

The most commonly used radiation imaging method is a method using a combination of a so-called "fluorescent plate" (or "intensifying screen") which emits fluorescence by radiation and a silver halide film.

[0004] In the above-described radiation imaging method, first, a target is irradiated with radiation, and radiation transmitted through the target is subjected to radiation.
After converting the light into visible light by a fluorescent plate to form a latent image on the silver halide film, the silver halide film is chemically treated to obtain a visible image. The film image (radiation image) obtained in this manner is a so-called analog photograph, and is used for medical diagnosis, inspection, and the like.

Further, a computed radiography apparatus (hereinafter, referred to as a “CR apparatus”) for acquiring a radiation image using an imaging plate (hereinafter, referred to as “IP”) coated with a stimulable phosphor as a phosphor. Is also being used.

[0006] In the CR device, when secondary excitation is performed by visible light such as a red laser with respect to IP that is primary excited by irradiation with radiation, light emission called stimulable fluorescence is generated. A radiation image is acquired by detecting with a light sensor such as a multiplier, and a visible image is output to a photographic photosensitive material, a CRT, or the like based on the data of the radiation image.

[0007] The CR apparatus is a digital photographing apparatus, but is an indirect digital photographing apparatus because it requires an image forming process of reading by secondary excitation. Here, the reason for being referred to as “indirect” is similar to the above-described apparatus for acquiring an analog radiation image such as an analog photograph (hereinafter, referred to as “analog photographing apparatus”).
This is because a radiation image cannot be displayed immediately.

On the other hand, in recent years, as an image receiving means for acquiring a radiation image from radiation passing through an object, a photoelectric conversion device in which pixels including minute photoelectric conversion elements and switching elements are arranged in a grid pattern has been used. Techniques for acquiring digital radiation images have been developed.

For example, US Pat. No. 5,418,377, US Pat. No. 5,39, and US Pat. No. 5,39,39 apply to a radiation imaging apparatus having a structure in which a phosphor is laminated on a sensor such as a CCD or an amorphous silicon two-dimensional image pickup device employing the above-described technology.
6,072 "," USP 5,381,014 "," US
P5,132,539 "and" USP4,810,8
81 "and the like. Such a radiographic apparatus is directly regarded as a digital radiographic apparatus because it can immediately display acquired radiographic image data.

The advantages of an indirect or direct digital photographing apparatus over an analog photographing apparatus include filmless operation,
It is possible to enlarge acquired information by image processing, to create a database, and the like. An advantage of the direct digital photographing apparatus over the indirect digital photographing apparatus is immediacy. For example, a radiographic image obtained by imaging can be instantaneously displayed on the spot, which is effective in an urgent medical site.

When the above-described radiation imaging apparatus is used as a medical apparatus and the radiation transmission density of a subject as an object is detected, scattering generated when the radiation passes through the subject is detected. In order to reduce the effects of the lines, a scattered radiation removing member usually called a “grid” is installed between the subject and a radiation transmission density detector (hereinafter, also simply referred to as a “detector”).

The grid is made of, for example, a material that is hard to transmit radiation, such as lead, and a material that is easy to transmit radiation, such as aluminum, each having a thin foil shape, and is alternately perpendicular to the radiation irradiation direction. Are arranged in a row. With such a configuration, radiation having an angle from the irradiation axis, such as scattered radiation in the subject, generated by irradiation of the subject with the radiation is absorbed by the lead foil in the grid before reaching the detector. Therefore, a radiographic image with high contrast can be obtained.

Here, if the grid is stopped during imaging, the radiation reaching the lead in the grid absorbs not only scattered radiation but also primary radiation, similarly.
In the detection unit, the density difference as it is in the grid arrangement is distributed, resulting in a striped radiation image. This is inconvenient for interpretation at the time of diagnosis or the like.

Therefore, in order not to cause the above phenomenon,
A radiation imaging apparatus having a mechanism for moving a grid during imaging has already been commercialized.

[0015]

However, in the conventional radiation imaging apparatus having the grid as described above,
Regardless of the light receiving method using a sensor such as a CCD or amorphous silicon two-dimensional image sensor, signal reading in the two-dimensional solid-state image sensor is a real-time electrical process.
There has been a problem with the influence of the vibration of the photographing unit and the electromagnetic influence of the drive motor due to the grid movement, which have not been a problem with indirect digital photographing apparatuses such as analog photographing apparatuses and CR apparatuses.

Specifically, a capacitor, a signal line, and the like fluctuate due to the influence of the vibration of the photographing unit due to the movement of the grid, the minute electric capacity fluctuates, and noise is superimposed on the radiation image. Also, when a motor is driven to move the grid in the vicinity of the signal readout by the sensor, the signal potential and control power supply potential fluctuate due to the influence of electromagnetic noise, which causes noise on the radiation image. Are superimposed. Therefore, in a radiographic image on which noise has been superimposed, for example, the medical diagnostic capability may be reduced.

On the other hand, a sensor such as a two-dimensional solid-state imaging device
Even in the non-exposure state, the charge accumulated in the sensor increases in proportion to the signal accumulation time due to the influence of the dark current. As the charge that does not contribute to the image signal increases, a larger noise is added to the output image signal.

Therefore, it is desired to optimize the photographing control so as to shorten the accumulation time in the sensor as much as possible while eliminating the influence of the grid vibration. However, there has been no apparatus or system that realizes this.

Therefore, the present invention has been made to eliminate the above-mentioned drawbacks, and has a configuration for preventing image quality deterioration due to electromagnetic noise and vibration caused by grid movement.
Provided is an imaging device, an imaging system, an imaging control method, and a storage medium in which a computer stores a processing step for executing the imaging device, an imaging system, and an imaging control method capable of providing an optimal high-quality captured image for medical diagnosis and the like. With the goal.

[0020]

For such a purpose,
According to a first aspect of the present invention, there is provided an image capturing apparatus having a function of receiving an object light via a movable grid by an image capturing element and reading out a stored signal obtained by photoelectric conversion in the image capturing element as a captured image signal. Stop the movement drive of
A control means is provided for starting reading of the stored signal of the image pickup device after the stop of the movement drive.

According to a second aspect of the present invention, in the first aspect,
An irradiation detection unit for detecting irradiation of the subject is provided, and the control unit controls the stop of the movement driving of the grid based on a detection result of the irradiation detection unit.

According to a third aspect, in the first aspect,
The control means may start reading out the stored signal of the image sensor after a predetermined time has elapsed after the driving of the movement of the grid is stopped.

According to a fourth aspect, in the third aspect,
The control means may determine the predetermined time in advance based on at least one of an irradiation time for the subject and a moving speed of the grid.

According to a fifth aspect based on the first aspect,
Vibration detecting means for detecting a vibration state of the image sensor due to movement of the grid, wherein the control means controls reading start of an accumulation signal of the image sensor based on a detection result of the vibration detecting means. It is characterized by.

According to a sixth aspect, in the first aspect,
The irradiation of the subject includes radiation irradiation.

According to a seventh aspect of the present invention, there is provided an imaging system in which a plurality of devices are communicably connected to each other, wherein at least one device among the plurality of devices is according to any one of claims 1 to 6. It has a function of a photographing device.

According to an eighth aspect of the present invention, there is provided an imaging control method including a processing step of receiving radiation transmitted through a subject through a movable grid by an image sensor and reading out a stored signal of the image sensor. The method includes a step of stopping the driving for moving the grid, and starting reading the accumulated signal of the image sensor after stopping the driving for moving the grid.

According to a ninth aspect, in the eighth aspect,
The processing step includes a step of recognizing the irradiation period of the radiation, and a step of stopping the movement driving of the grid based on the recognition of the irradiation period.

In a tenth aspect based on the eighth aspect, in the processing step, after stopping the movement of the grid, reading of the stored signal of the image sensor is started after a predetermined appropriate waiting time. It is characterized by including a step.

In an eleventh aspect based on the tenth aspect, the processing step includes a step of determining the appropriate standby time according to at least one of the radiation irradiation time and the grid moving speed. It is characterized by including.

In a twelfth aspect based on the eighth aspect, the processing step includes a step of detecting a convergence of the vibration of the image pickup device and a step of detecting the convergence of the vibration.
A step of starting to read out the stored signal of the image sensor.

In a thirteenth aspect based on the eighth aspect, the radiation includes X-rays.

According to a fourteenth aspect of the present invention, a computer stores a processing program for implementing the function of the image capturing apparatus according to any one of claims 1 to 6 or the function of the image capturing system according to claim 7. It is characterized by being a storage medium.

According to a fifteenth aspect of the present invention, a computer-readable storage medium stores a processing program for performing the image capturing control method according to any one of claims 8 to 13.

[0035]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) The present invention provides, for example,
It is applied to a radiation imaging system 100 as shown in FIG.

<Arrangement of Radiation Imaging System 100> As shown in FIG. 1, the radiation imaging system 100 includes an imaging device 110 for acquiring a captured image signal of a subject (examinee) 102, and the overall operation of the system 100. A control device 111 for controlling the control device, a storage device 112 for storing a processing program for control processing in the control device 111 and various data such as captured images, and a display device 113 for displaying captured images and the like
And an image processing apparatus 11 that performs arbitrary image processing on a captured image signal of the subject 102 obtained by the imaging apparatus 110
4, a photographing condition instructing device 115 for instructing various photographing conditions in the photographing device 110, a photographing button 116 for instructing the system 100 to start a photographing operation,
Radiation (X-rays, etc.) is applied to the subject 102 by the radiation tube 1
01 and a radiation generating apparatus 117 are connected to each other via a system bus 120 so as to be able to exchange data.

The imaging device 110 is installed at a position where the radiation generated from the radiation tube 101 of the radiation generator 117 can be received through the subject 102.
Chest pad 103, grid 104, phosphor 105, sensor (such as two-dimensional solid-state image sensor) 106, signal reading unit 10
7 and a grid moving unit 108. Chest pad 103, grid 104, phosphor 105, and sensor 1
06 is the radiation tube 1 of the radiation generator 117 in this order.
They are arranged from the side closer to 01.

<A series of operations of the radiation imaging system 100> Here, an outline of an imaging procedure in the radiation imaging system 100 and a process of generating a radiation image will be described.

First, the user (radiologist or the like) positions the subject 102 with respect to the chest pad 103 and uses the imaging condition instructing device 115 to set appropriate imaging conditions (for example, tube voltage,
Tube current, irradiation time, type of sensor 106, radiation tube 1
01 type). Note that, in the present embodiment, the input of the photographing condition is a manual input from the user by the photographing condition instruction device 115. However, the present invention is not limited to this. For example, the photographing condition is connected to the photographing device 110. The information may be input via a network (not shown).

Next, the user presses the shooting button 116 to request the control device 111 to start a shooting operation. After accepting the photographing operation start request from the user, the control device 111 performs necessary initialization in the system 100 and urges the radiation generation device 117 to irradiate the radiation.

The radiation generator 117 includes a controller 111
Radiation is generated from the radiation tube 101 in accordance with the irradiation instruction from. Radiation generated from the radiation tube 101 passes through the subject 102 and reaches the chest pad 103.

The chest pad 103 is exposed to radiation transmitted through the subject 102 with a transmitted radiation distribution according to the structure of the subject 102. Further, since the chest pad 103 is configured to be sufficiently transparent to radiation, the radiation transmitted through the chest pad 103 reaches the grid 104.

The grid 104 removes the scattered radiation component in the radiation transmitted through the chest pad 103 and allows only the effective radiation to reach the phosphor 105. The phosphor 105 transmits radiation (effective radiation) from the grid 104 to the sensor 106.
It is made visible so as to match the spectral sensitivity of.

The sensor 106 receives radiation from the phosphor 105 and accumulates the radiation as an electric signal (image signal) by two-dimensional photoelectric conversion according to the two-dimensional distribution light intensity. The signal reading unit 107 includes the sensor 10
The stored image signal in step 6 is read out and stored in the storage device 112 as a radiation image signal.

The image processing device 114 performs appropriate image processing on the radiation image signal stored in the storage device 112. The display device 113 displays the radiation image signal after the processing by the image processing device 114.

<Operation and Configuration Most Characteristic of Radiation Imaging System 100> FIG. 2 shows an operation control process of the system 100 executed by the control device 111.
FIG. 3 shows the timing of the operation control. Note that the process shown in FIG. 2 is a process from the input of the shooting conditions by the user to the reading of the image signal by the sensor 106.

Step S201: The control device 111 determines the irradiation time Texp, the type of the sensor 106 used for imaging, and the type of the radiation tube 101 according to the imaging conditions selected and input by the user with the imaging condition indicating device 115. And recognize. Then, the control device 111 performs control up to radiation irradiation and control after radiation irradiation from the recognition information,
It is determined by the processing from the next step S202.

Step S202: The control device 111 determines the sensor initialization time Tss according to the type of the sensor 106. Although the sensor initialization time Tss varies depending on the type of the sensor 106, if the sensor 106 is, for example, a sensor that requires a preliminary discharge of dark current, the idle reading time becomes the sensor initialization time Tss. From this time, Signal accumulation in the sensor 106 starts.

Step S203: The control device 111 determines a grid initialization time Tgs and a grid vibration convergence time Tge from the irradiation time Texp.

More specifically, first, in order to reduce the appearance of streaks on the grid 104, for example, 10
It is necessary to pass through the stripes of the cycle or more. On the other hand, the moving distance of the grid 104 is limited. Therefore, it is necessary to optimize the moving speed of the grid 104 according to the irradiation time Texp. Since the grid 104 generally has a focus, it is necessary to align the center position of the radiation with the center position of the grid 104 in order to obtain good image quality of a captured image. Therefore, the optimal moving speed of the grid 104 (target moving speed) and the time required for the position of the grid 104 to reach the radiation irradiation center position (target position) are:
This is the grid initialization time Tgs.

In this embodiment, the grid initialization time Tg at which the target moving speed and position of the grid 104 are reached
s and the grid vibration convergence time Tge required for the device vibration generated during the movement to converge are experimentally obtained in correspondence with, for example, the irradiation time Texp of various patterns and the moving speed of the grid 104. A table is stored in the storage device 112 in advance. Thus, the grid initialization time Tgs and the grid vibration convergence time Tge corresponding to the actually obtained irradiation time Texp may be determined from the tabulated information in the storage device 112.

Step S204: The control device 111 determines the pre-irradiation delay time T based on the type of the radiation tube 101.
xs and the post irradiation delay time Txe are determined.

The pre-irradiation delay time Txs is the time from when the radiation generator 117 is instructed to irradiate radiation to when the radiation generator 117 actually starts irradiating the radiation. And the type of the radiation tube 101. In the present embodiment, for example, the radiation generator 117 or the radiation tube 101
Pre-irradiation delay time Txs corresponding to various types of
Are tabulated and prepared in advance, and the corresponding pre-irradiation delay time Txs is determined from the tabulated information.

The post-irradiation delay time Txe is a delay time from the elapse of the irradiation time Texp until the radiation irradiation of the radiation generator 117 actually ends. The post irradiation delay time Txe is determined in the same manner as the pre irradiation delay time Txs.

Step S205: The control device 111 determines the irradiation delay time T1. Irradiation delay time T1
Is a delay time from when the user issues a radiographing request with the radiographing button 116 to when the radiation generator 117 actually irradiates the radioactive rays.
02, the sensor initialization time Tss determined in step S203, the grid initialization time Tgs determined in step S203, and the pre-irradiation delay time Txs determined in step S204 are the irradiation delay time T1.
Is determined as

Step S206: The control device 111 determines a time table until the irradiation. This time table is determined from the sensor initialization time Tss determined in step S202, the grid initialization time Tgs determined in step S203, and the pre-irradiation delay time Txs determined in step S204.

Specifically, after recognizing that the user has issued a photographing request with the photographing button 116, the sensor 1
The control sequence and the time (timing) of the initialization of 06, the start of driving of the grid 104, and the radiation irradiation instruction (permission of irradiation) to the radiation generator 117 are determined based on the irradiation delay time T1 determined in step S205. Determined by the result of the subtraction. That is, the initialization timing of the sensor 106 is determined as “T1-Tss”,
The drive start timing of the grid 104 is set to "" T1-T
gs ”, and sets the timing of the radiation irradiation instruction (irradiation permission) to the radiation generator 117 to“ T1-Tx ”.
s ".

Step S207: After deciding the control before irradiation as described above, the control device 111
It is determined whether or not a photographing request has been made by the user using the photographing button 116, and the apparatus enters a standby state until the photographing request is made.

Step S208: When the control device 111 recognizes that the user has made a photographing request using the photographing button 116, the control device 111 executes operation control according to the time table determined in step S206. Thereby, the initialization of the sensor 106 is executed after the lapse of "T1-Tss", the driving of the grid 104 is executed after the lapse of "T1-Tgs", and the irradiation permission is executed after the lapse of "T1-Txs".

Step S209: The control device 111 sets the irradiation time (actual irradiation time) T determined in step S201.
exp, post irradiation delay time Txe determined in step S204, and irradiation delay time T1 determined in step S205 (T1 + Texp + T
It is in a standby state until xe) elapses.

Step S210: The control device 111
Upon recognizing that the “T1 + Texp + Txe” time has elapsed, the grid 104 via the grid moving unit 108 is recognized.
Stop driving.

Step S211: The control device 111 sets the grid vibration convergence time Tg determined in step S203.
It waits until e elapses.

Step S212: When the control device 111 recognizes that the grid vibration convergence time Tge has elapsed, the control device 111 starts reading the accumulated signal of the sensor 106 via the signal reading section 107.

In the operation control of the radiation imaging system 100 shown in the flow chart of FIG. 2, in particular, after the irradiation time Texp elapses, a standby state is further set for the post irradiation delay time Txe. Reflection can be prevented. Also,
Since the driving of the grid 104 is stopped, it is possible to prevent the influence of the electromagnetic noise generated from the grid moving unit 108. Further, after the driving of the grid 104 is stopped, the system is set to the standby state of the grid vibration convergence time Tge, so that the influence of the apparatus vibration can be prevented. Therefore, after recognizing the photographing request from the user, the control device 111 controls the operation of the present system 100 according to the flowchart of FIG. 2 described above, so that a good photographed image can be obtained.

The operation of the radiation imaging system 100 described above will be described more specifically with reference to the timing chart of FIG. 3 as follows. Note that the timing chart of FIG. 3 illustrates the timing from when the shooting button 116 is pressed.

First, for example, the irradiation time Texp = 100 ms, the sensor initialization time Tss = 200 ms, the grid initialization time Tgs = 300 ms, the pre-irradiation delay time Txs = 100 ms, the grid vibration convergence time Tge = 300 ms, and the photographing conditions input by the user. The irradiation delay time Txe = 100 ms is determined. In this case, the irradiation delay time T1 is the longest time among the sensor initialization time Tss, the grid initialization time Tgs, and the pre-irradiation delay time Txs, so that T1 = max (Tss, Tgs, Txs) = Tgs = 3
00 ms. The operation control up to the irradiation of radiation is determined from these initial conditions.

Next, sensor initialization, grid movement start,
The control timing for the instruction to permit irradiation and after the recognition of the photographing request is obtained by subtracting the time required for the operation from the irradiation delay time T1. Therefore, sensor initialization timing: T1-Tss = 100m
s Grid movement start timing: T1-Tgs = 0 ms Irradiation permission signal transmission timing: T1-Txs = 200 m
s

Then, the control timing after the irradiation of the radiation is determined by adding the irradiation time Texp and the post-irradiation delay time Txe to the irradiation delay T1 and then stopping the movement control of the grid 104 after the lapse of the actual sunlight time. After the vibration convergence time Tge has elapsed, the sensor 10
6 is started. That is, the grid control stop timing and the signal read start timing are set as grid control stop timing: T1 + Texp + Txe
= 500 ms Signal read start timing: T1 + Texp + Txe + T
ge = 800 ms.

After the above determination of the control timing is completed, a photographing request (see FIG. 3A) from the user by pressing the photographing button 115 is awaited. When the imaging request is recognized, the operation control of the radiation imaging system 100 is started based on the control timings determined above.

That is, first, as shown in FIG. 3B, the movement (movement) of the grid 104 is started. As shown in FIG. 3C, the moving speed of the grid 104 accelerates and reaches an irradiation enabled state after 300 ms (grid initialization time Tgs = 300 ms).

Next, as shown in FIG. 3 (f), 100 ms (sensor initialization timing:
After T1-Tss = 100 ms, initialization of the sensor 106 is started, and 200 ms (sensor initialization time Tss)
= 200 ms), the initialization of the sensor 106 ends.

Next, as shown in FIG. 3D, irradiation is instructed to the radiation generator 117 200 ms (irradiation permission signal transmission timing: T1−Txs = 200 ms) after the recognition of the imaging request. As a result, in the radiation generator 117, as shown in FIG.
After 0 ms (pre-irradiation delay time Txs = 100 ms), actual irradiation is started.

Then, 500 ms from the recognition of the photographing request.
(Grid control stop timing: T1 + Texp + Tx
After e = 500 ms), the actual irradiation by the radiation generator 117 ends. At this time, as shown in FIG. 3B, the movement control of the grid 104 is stopped. As a result, the moving speed of the grid 104 gradually decreases.
Along with this, the vibration of the imaging device 110 generated by moving the grid 104 starts to converge.

Thereafter, as shown in FIG. 3 (f), 800 ms (signal read start timing: T1 + Texp + Txe + Tge = 800 ms) after the photographing request is recognized, the signal readout unit 107 stops signal accumulation in the sensor 106. Then, an instruction to start the signal reading is issued. At this time, the vibration of the photographing device 110 is reduced so as not to affect the image quality, and as a result, a good photographed image can be obtained.

(Second Embodiment) The present invention provides, for example,
It is applied to a radiation imaging system 300 as shown in FIG. The radiation imaging system 300 has the same configuration as that of the radiation imaging system 100 shown in FIG. 1 described above. However, a radiation detector 302 for detecting a radiation irradiation state and a vibration state of the grid 104 are measured in the imaging apparatus 110. And a vibration measuring device 301 that performs the measurement.

The radiation imaging system 300 shown in FIG.
In the figure, parts that operate in the same manner as the radiation imaging system 100 of FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. Here, the radiation imaging system 1 of FIG.
Only the configuration different from 00 will be specifically described.

FIG. 5 shows a control device 111 according to this embodiment.
FIG. 6 shows the operation control processing of the present system 100 which is executed, and FIG. 6 shows the timing of the operation control.

In the flowchart of FIG.
Steps that perform the same processing as the processing steps in the flowchart shown in FIG. 2 are denoted by the same reference numerals, and details thereof are omitted.

Step S201: The control device 111 determines the irradiation time Texp, the type of the sensor 106 used for imaging, and the type of the radiation tube 101 according to the imaging conditions selected and input by the user with the imaging condition indicating device 115. And recognize. Then, the control device 111 performs control up to radiation irradiation and control after radiation irradiation from the recognition information,
It is determined by the processing from the next step S202.

Step S202: The control device 111 determines the sensor initialization time Tss according to the type of the sensor 106.

Step S203 ': The control device 111
From the irradiation time Texp, a grid initialization time Tgs (time to reach the target moving speed and position of the grid 104) is determined.

Step S204 ': The control device 111
The pre-irradiation delay time Txs (the time from when the radiation generator 117 is instructed to permit radiation irradiation to when the radiation generator 117 actually starts irradiation) is determined according to the type of the radiation tube 101. .

Step S205: The controller 111 sets the irradiation delay time T1 (sensor initialization time Tss, grid initialization time Tgs, and pre-irradiation delay time Txs).
The longest time).

Step S206: The control device 111 sets the timing for initializing the sensor 106 to "T1-Tss", the timing for starting the driving of the grid 104 to "T1-Tgs" as a time table until irradiation, The timing of the radiation irradiation instruction (irradiation permission) for 117 is determined as “T1-Txs”.

Step S207: After deciding the control before the radiation irradiation as described above,
It is determined whether or not a photographing request has been made by the user using the photographing button 116, and the apparatus enters a standby state until the photographing request is made.

Step S208: When the control device 111 recognizes that the user has made a photographing request using the photographing button 116, the control device 111 executes operation control according to the time table determined in step S206. Thereby, the initialization of the sensor 106 is executed after the lapse of "T1-Tss", the driving of the grid 104 is executed after the lapse of "T1-Tgs", and the irradiation permission is executed after the lapse of "T1-Txs".

Step S209 ': The control device 111
Based on the detection signal output from the radiation detector 302, it is determined whether the radiation irradiation by the radiation generator 117 has been completed.

Step S210: When the control device 111 recognizes that the radiation irradiation by the radiation generator 117 has been completed, the control device 111
4 is stopped.

Step S211 ': The control device 111
According to the measurement result of the vibration measuring device 301, the grid 104
It is determined whether or not the vibration has converged.

Step S212: When the control unit 111 recognizes that the vibration of the grid 104 has converged, the control unit 111 starts reading out the accumulated signal of the sensor 106 via the signal reading unit 107.

In the operation control of the radiation imaging system 100 shown in the flowchart of FIG. 5, when it is recognized that the radiation irradiation has been completed based on the detection result of the radiation detector 302, the driving of the grid 104 is stopped. With the configuration, the effect of electromagnetic noise generated from the grid moving unit 108 can be prevented. Further, after the driving of the grid 104 is stopped, the standby state is set until the vibration of the grid 104 converges based on the measurement result of the vibration measuring device 301, so that the influence of the device vibration can be prevented. Therefore, after recognizing the photographing request from the user, the control device 111 controls the operation of the present system 100 according to the flowchart of FIG. 5 described above, so that a good photographed image can be obtained.

The operation of the radiation imaging system 100 as described above will be described more specifically with reference to the timing chart of FIG. 6 as follows. Note that the timing chart of FIG. 6 describes the timing from when the shooting button 116 is pressed.

First, for example, the irradiation time Texp = 100 ms, the sensor initialization time Tss = 200 ms, the grid initialization time Tgs = 300 ms, and the pre-irradiation delay time Txs = 100 ms are determined based on the photographing conditions input by the user. In this case, the irradiation delay time T1 is the longest time among the sensor initialization time Tss, the grid initialization time Tgs, and the pre-irradiation delay time Txs, so that T1 = max (Tss, Tgs, Txs) = Tgs = 3
00 ms. The operation control up to the irradiation of radiation is determined from these initial conditions.

Next, sensor initialization, grid movement start,
The control timing for the instruction to permit irradiation and after the recognition of the photographing request is obtained by subtracting the time required for the operation from the irradiation delay time T1. Therefore, sensor initialization timing: T1-Tss = 100m
s Grid movement start timing: T1-Tgs = 0 ms Irradiation permission signal transmission timing: T1-Txs = 200 m
s

After the above determination of the control timing is completed, a photographing request by the user pressing the photographing button 115 (see FIG. 6A) is waited. When the imaging request is recognized, the operation control of the radiation imaging system 100 is started based on the control timings determined above.

That is, first, as shown in FIG. 6B, the movement (movement) of the grid 104 is started. At the same time, as shown in FIG.
4 outputs a vibration detection signal indicating that it is in a moving state.
Level. The moving speed of the grid 104 is as shown in FIG.
As shown in (c), it rises at an accelerated rate, and reaches an irradiation enabled state after a lapse of 300 ms (grid initialization time Tgs = 300 ms).

Next, as shown in FIG. 6H, 100 ms (sensor initialization timing:
After T1-Tss = 100 ms, initialization of the sensor 106 is started, and 200 ms (sensor initialization time Tss)
= 200 ms), the initialization of the sensor 106 ends.

Next, as shown in FIG. 6D, irradiation is instructed to the radiation generator 117 200 ms (irradiation permission signal transmission timing: T1−Txs = 200 ms) after the recognition of the imaging request. As a result, in the radiation generator 117, as shown in FIG.
After 0 ms (pre-irradiation delay time Txs = 100 ms), actual irradiation is started. At the same time, FIG.
As shown in (f), a radiation detection signal indicating radiation irradiation is set to a high level.

Then, when the radiation irradiation is completed and the output of the radiation detector 302 falls below a predetermined threshold value, it is determined that the irradiation is completed, and the radiation detection signal is changed to the low level as shown in FIG. I do. Accordingly, FIG.
As shown in (b), the movement control of the grid 104 is stopped. As a result, the moving speed of the grid 104 gradually decreases. The vibration state of the grid 104 at this time is observed by the vibration measuring device 301.

When it is recognized that the vibration of the photographing device 110 caused by moving the grid 104 has begun to converge and the output of the vibration measuring device 301 has dropped below a predetermined vibration amount, as shown in FIG. , The vibration detection signal is set to the low level. Then, as shown in FIG. 6H, an instruction is given to the signal reading unit 107 to terminate the signal accumulation in the sensor 106 and start the signal reading. At this time, the vibration of the photographing device 110 is reduced so as not to affect the image quality, and as a result, a good photographed image can be obtained.

An object of the present invention is to provide a storage medium storing program codes of software for realizing the functions of the host and the terminal according to the first and second embodiments to a system or an apparatus, and to provide the system or apparatus with the storage medium. By reading and executing the program code stored in the storage medium by the computer (or CPU or MPU) of the device,
Needless to say, this is achieved. In this case, the program code itself read from the storage medium is the first and second program codes.
The functions of the embodiment are realized, and the storage medium storing the program code constitutes the present invention. ROM, floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-R
An OM, a CD-R, a magnetic tape, a nonvolatile memory card, or the like can be used. The functions of the first and second embodiments are realized by executing the program code read by the computer, and the OS running on the computer based on the instruction of the program code. Do some or all of the actual processing,
It goes without saying that the processing may realize the functions of the first and second embodiments. Further, after the program code read from the storage medium is written to a memory provided in an extension function board inserted into the computer or a function extension unit connected to the computer, the function extension is performed based on the instruction of the program code. It goes without saying that the CPU included in the board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the first and second embodiments.

[0103]

As described above, according to the present invention, the influence of the electromagnetic noise due to the grid movement can be eliminated by stopping the grid before starting the reading of the signal stored in the image sensor. it can. This allows
Noise is not superimposed on a captured image (radiation image or the like) obtained from a readout signal from the image sensor, and a high-quality captured image can be obtained. Also,
When a certain standby time is provided after the grid is stopped, the signal reading from the image sensor is started after the influence of the vibration of the image sensor due to the movement of the grid is reduced. Images can be obtained.
Therefore, it is possible to prevent the image quality of the captured image from deteriorating due to the influence of electromagnetic noise due to the grid movement, and to prevent the image quality of the captured image from deteriorating due to the vibration of the image sensor due to the grid movement. For example, if the present invention is applied to radiography, a good radiographic image without noise can be provided, so that erroneous diagnosis or the like in image diagnosis can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a radiation imaging system to which the present invention is applied in a first embodiment.

FIG. 2 is a flowchart illustrating an operation of the radiation imaging system.

FIG. 3 is a diagram for explaining operation control timing of the radiation imaging system.

FIG. 4 is a block diagram showing a configuration of a radiation imaging system to which the present invention is applied in the second embodiment.

FIG. 5 is a flowchart for explaining the operation of the radiation imaging system.

FIG. 6 is a diagram for explaining operation control timing of the radiation imaging system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 radiation imaging system 101 radiation tube 102 subject 103 chest pad 104 grid 105 phosphor 106 sensor (two-dimensional image sensor) 107 signal readout unit 108 grid moving unit 110 imaging device 111 control device 112 storage device 113 display device 114 image Processing device 115 Imaging condition indicating device 116 Imaging button 117 Radiation generation device 120 System bus

Claims (15)

[Claims] 1. An imaging device having a function of receiving an object light via a movable grid by an image sensor and reading out a stored signal by photoelectric conversion in the image sensor as a captured image signal. An image capturing apparatus, comprising: a control unit configured to stop a moving drive and start reading out an accumulation signal of the image sensor after the moving drive is stopped. 2. An apparatus according to claim 1, further comprising: an irradiation detection unit configured to detect irradiation of the subject, wherein the control unit controls a stop of the movement driving of the grid based on a detection result of the irradiation detection unit. Item 7. The imaging device according to Item 1. 3. The system according to claim 1, wherein the control means starts reading out the stored signal of the image sensor after a predetermined time has elapsed after the movement of the grid is stopped.
The imaging device according to the above. 4. The control means sets the predetermined time as:
4. The photographing apparatus according to claim 3, wherein the photographing apparatus is determined in advance based on at least one of an irradiation time for the subject and a moving speed of the grid. 5. A vibration detecting means for detecting a vibration state of the image sensor due to the movement of the grid, wherein the control means starts reading of a stored signal of the image sensor based on a detection result of the vibration detecting means. The photographing apparatus according to claim 1, wherein the photographing device performs control. 6. The photographing apparatus according to claim 1, wherein the irradiation of the subject includes radiation irradiation. 7. An imaging system in which a plurality of devices are communicably connected to each other, wherein at least one of the plurality of devices is a function of the imaging device according to any one of claims 1 to 6. An imaging system comprising: 8. An imaging control method including a processing step of receiving radiation transmitted through a subject by an image sensor via a movable grid and reading out a stored signal of the image sensor, wherein the processing step includes: Stopping the movement driving of the image pickup device and, after stopping the movement driving, reading the accumulated signal of the image sensor. 9. The method according to claim 8, wherein the processing step includes a step of recognizing the irradiation period of the radiation, and a step of stopping the movement driving of the grid based on the recognition of the irradiation period.
The shooting control method described in the above. 10. The above-mentioned processing step, after stopping the movement driving of the grid, after a predetermined appropriate waiting time,
9. The method according to claim 8, further comprising the step of starting to read out the stored signal of the image sensor. 11. The method according to claim 10, wherein the processing step includes a step of determining the appropriate waiting time according to at least one of the irradiation time of the radiation and the moving speed of the grid. Shooting control method. 12. The method according to claim 1, wherein the processing step includes a step of detecting a convergence of the vibration of the image sensor, and a step of starting reading out a stored signal of the image sensor based on the detection of the vibration convergence. The photographing control method according to claim 8. 13. The imaging control method according to claim 8, wherein said radiation includes X-rays. 14. A processing program for implementing the function of the photographing apparatus according to claim 1 or the function of the photographing system according to claim 7, readable by a computer. Storage medium. 15. A storage medium, wherein a processing program for implementing the imaging control method according to claim 8 is readable by a computer.