JP5241047B2 - Digital radiation imaging apparatus, information processing apparatus, radiation imaging apparatus, control method for digital radiation imaging apparatus, control method for information processing apparatus, and control method for radiation imaging apparatus - Google Patents

Description

BACKGROUND OF THE INVENTION
The present invention relates to a digital radiation imaging apparatus, an information processing apparatus, a radiation imaging apparatus, a digital radiation imaging apparatus control method, an information processing apparatus control method, and a radiation imaging apparatus control method.

  A method of irradiating an object with radiation, detecting an intensity distribution of the radiation transmitted through the object, and obtaining a radiation image of the object is widely used in industrial nondestructive inspection and medical diagnosis. The most common method for obtaining a radiographic image of an object. The most common method is to combine a so-called “fluorescent screen” (or intensifying screen) that emits fluorescence with radiation and a silver salt film to irradiate the object with radiation. In this method, a radiation image is converted to visible light with a fluorescent plate, a latent image is formed on the silver salt film, and then the silver salt film is chemically treated to obtain a visible image. The radiographic image obtained by this imaging method is a so-called analog photograph and is used for diagnosis, inspection, and the like.

  On the other hand, recently, a technique for acquiring a digital image by using a photoelectric conversion device in which pixels including minute photoelectric conversion elements, switching elements, and the like are arranged in a lattice form as an image receiving means has been developed. USP5418377, USP5396072, USP5381014, USP5132539, USP4810881, etc. are disclosed as a radiation imaging apparatus in which a phosphor is laminated on a CCD or amorphous silicon two-dimensional imaging device. These photographing devices can display acquired image data immediately, and can be directly called digital photographing devices.

  The advantages of digital photography devices over analog photography technology include:

  That is, filmless, expansion of acquired information by image processing, creation of a database, and the like. Further, the immediate digital imaging device has an advantage over the indirect digital imaging device in terms of immediacy. The ability to instantly display a captured image on the spot is advantageous in a medical site that requires urgent action.

Problems to be solved by the invention

  However, regardless of the light receiving method such as CCD or amorphous silicon, the two-dimensional imaging device has a characteristic that dark current is accumulated even in the absence of a signal, which contributes to noise in photographing a small signal and has a high gradation (= (Approx. 4096 gradations), it may cause a reduction in image quality. In addition, since this dark current changes depending on the ambient temperature and the like, it is necessary to perform imaging in a series of imaging sequences. For this reason, it takes about 3 to 4 seconds to display on the monitor from the start of shooting.

  FIG. 5 shows a configuration diagram of a radiation imaging apparatus that acquires this digital image. In FIG. 5, 1 is a radiation imaging means (hereinafter referred to as “sensor unit”), 2 is a control PC, 20 is a monitor, 21 is a printer, and 22 is a data storage device.

  Reference numeral 101 denotes a two-dimensional image sensor, and reference numeral 102 denotes an amplifier circuit that adjusts the gain of the image signal level output from the two-dimensional image sensor 101. Reference numeral 103 denotes an A / D converter that converts an analog imaging signal into digital. Reference numeral 104 denotes a line memory for storing one line of the digital signal output from the A / D converter 103. Reference numeral 105 denotes two line memories. This is a multiplex IC that converts the output of 104 into a serial signal output of one line.

  Further, a drive pulse required by the two-dimensional image sensor 101, a sampling pulse required by the A / D converter 103, and other necessary timing signals are supplied from the pulse generator. The pulse generator 108 is controlled by 109 MPUs. Reference numeral 107 denotes a communication IC for transferring the output of the multiplex IC 105 to the control PC 2. The control PC 2 performs image processing on the digital signal transferred from the communication IC 107, displays it on the connected monitor 20, prints it on the printer 21, and stores it in the data storage device 22.

  The imaging sequence will be described below with reference to FIGS.

  FIG. 6A shows the state transition of the two-dimensional image sensor, and FIG. 6B shows the operation of the control PC.

  When there is a request to start imaging, the two-dimensional imaging device is brought into a uniform state in which the imaging devices of the two-dimensional imaging device are reset from the imaging standby state, and at the same time as X-ray exposure is performed, charge accumulation starts. This signal accumulation time PQ is proportional to the X-ray irradiation time. The accumulated signal charge is read as an S signal to the amplifier circuit 102, sequentially converted into a digital signal by the A / D converter 103, and transferred to the control PC 2 as image data SQ based on the S signal. The transfer time at this time is TSQ.

  When the reading of the S signal is completed (when the transfer of the S signal is completed), the state of the two-dimensional imaging device is reset, and dark current signal accumulation is performed in the same accumulation time PQ as in S signal imaging. The accumulated signal charge is read out as an F signal, processed in the same manner as the S signal, and transferred to the control PC 2 as image data FQ based on the F signal. The transfer time at this time is TFQ. After the transfer is completed, the two-dimensional image sensor stands by in a shooting standby state until the next shooting request is made.

  The control PC 2 receives the image data SQ based on the S signal imaged by the two-dimensional image sensor from the standby state from the sensor unit 1 and stores it. When this transfer ends, the standby state is restored.

  Similarly, the F signal corresponding to the dark current is also transferred from the sensor unit 1, and the control PC receives and stores it as the image data FQ. The transfer time at this time is TFQ.

  The transfer times TSQ and TFQ of the S signal and the F signal are the same as the signal read time, respectively.

  When the transfer of the F signal is completed, the control PC performs simple image processing for performing simple image display. First, dark current correction (dark current correction (QQ) = SQ−FQ) is performed by subtracting the image data FQ from the transferred image data SQ. In the conventional example, the total number of pixels of the two-dimensional image sensor is 2688 × 2688 pixels, and image processing is performed to display 336 × 336 pixels of each side 1/8 on the monitor. This image processing time is TPQ, the display image displayed on the monitor is QQ, and the time from X-ray exposure to monitor display is tQ.

  This simple image display is a display for confirming the X-ray dose and the pre- and position of the captured image, and does not perform inspection or diagnosis on this image, but merely displays an outline of the imaging result. Next, the image data subjected to dark current correction is used to perform optimal image processing for inspection and diagnosis (this is referred to as “main image processing”), and the result is stored in the data storage device 22.

  Further, the captured image file can be called up and displayed on the monitor 20 or printed on the printer 21 as necessary.

  In the configuration of the conventional example, since the sensor unit 1 does not have a frame memory, the image data of all the pixels must be transferred to the control PC 2 despite the simple image display, and the transfer rate is the signal reading rate. It is required to be the same as the rate. Therefore, when the simple image processing and the main image processing are compared from the viewpoint of monitor display, there is no difference. In such a configuration, in order to increase the display speed of a simple image, for example, when transferring 14-bit image data serially, the transfer rate is about 800 Mbps. Therefore, a special and expensive communication circuit is required.

Means for solving the problem

[Means for Solving the Problems]
In order to solve the above problems, a digital radiation imaging apparatus according to the present invention mainly has the following configuration.

That is, the digital radiation imaging apparatus is a digital radiation imaging apparatus that communicates with an external apparatus including an image processing unit that performs image processing on image data and a display control unit that displays the image data that has been subjected to image processing on a display unit. ,
A two-dimensional imaging device that accumulates charges in response to X-ray exposure; an amplifier that amplifies an electrical signal based on the accumulated charges; and an AD converter that converts the amplified electrical signal into digital data; an imaging means comprising a
Storage means for memorize an X-ray image data based on the digital data,
A generating means for generating image data obtained some data in thinning Kukoto of the X-ray image data stored in the storage means,
Transfers image data said generated in the external device, after the transfer, starts the transfer of the image data including the data other than the image data the generated, the transfers of the stored X-ray image data A transfer means for completing
It is characterized by having.

<Embodiment 1>
An embodiment of a radiation imaging apparatus according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram illustrating the configuration of the radiation imaging apparatus. Here, in FIG. 1, the same reference numerals are given to the same components as those in the configuration diagram of the conventional example of FIG. 5, and detailed description of those described in the conventional example is omitted.

  In FIG. 1, there are two imaging signal output lines output from the two-dimensional imaging apparatus 101. However, in order to simplify the drawing, the number of imaging signal output lines that are actually output is defined. Not what you want.

  1 is a frame memory for storing at least one frame of signal output output from the multiplex IC 105, and 110 is a selector circuit for thinning and transferring the signal output for simple image display. .

  Hereinafter, the imaging sequence will be described with reference to FIGS.

  2A shows the state transition of the two-dimensional image sensor, FIG. 2B shows the state of the frame memory, and FIG. 2C shows the operation of the control PC.

  In the state of the two-dimensional image sensor, FIG. 2A, n in the figure represents the number of times of photographing. The contents of this processing sequence are the same as those in the conventional imaging sequence shown in FIG.

  When there is a request to start imaging in the imaging standby state, the two-dimensional imaging device 101 is in a uniform state in which each imaging element of the two-dimensional imaging device is reset from the imaging standby state, and X-ray exposure is performed. At the same time, charge accumulation begins. The signal accumulation time Pn is proportional to the X-ray irradiation time. The accumulated signal charge is read as an S signal by an amplifier (AMP) circuit 102, subjected to signal processing by an A / D converter 103, a line memory 104, and a multiplex IC 105, and the S signal converted into a digital signal is Are sequentially written in the frame memory 106 (FIG. 2B).

  When the two-dimensional imaging device finishes reading the S signal to the frame memory 106, it is reset to return to the uniform state, and then dark current signal accumulation is performed with the same accumulation time Pn as that during S signal imaging. The accumulated signal charge is read out as an F signal, processed in the same manner as the S signal, and written into the frame memory 106.

  When the readout of the F signal is completed, the two-dimensional image sensor returns to the imaging standby state until the next imaging request is made.

  Simultaneously with writing to the frame memory 106, the selector 110 sequentially performs signal thinning and transfer to the control PC 2 at a rate of one pixel per M pixel. Here, “M” is determined as a value suitable for a displayable pixel of the monitor 20. In the present embodiment, the total number of pixels of the two-dimensional image sensor is 2688 × 2688 pixels, and the displayable pixels of the monitor are 336 × 336 pixels, so that M = 8 (M = 2688/336). Accordingly, since the transfer rate to the control PC 2 can be transferred at a rate of 1 pixel per 8 pixels, the transfer rate is 1/8 of the signal read rate. The image data for the thinned S signal transferred to the control PC 2 is referred to as “image data SS” (FIG. 2C).

  The control PC 2 performs image processing using the transferred thinned image data SS and performs display control for simple image display. The dark current image data used in this image processing is subjected to dark current correction using the dark current image data (Fn-1) acquired in the previous photographing stored in the control PC. That is, the image data subjected to dark current correction is an image obtained by subtracting the dark current image data in the previous imaging from the thinned-out image data SS. If the display image subjected to dark current correction is Qn, Qn is expressed by the following equation. Defined by

Dark-current corrected image data (Qn) = SS−Fn−1
If this image processing time is TPn, the image processing time TPn is processed at a transfer rate of 1/8, so that the processing time in the entire two-dimensional image sensor is 1/64 compared with the conventional example. Thus, the processing time can be shortened (TPn (FIG. 2C)) <TPQ (FIG. 6B).

  Further, the time tn from the X-ray exposure to the monitor display is greatly shortened compared with the time tQ until the monitor display in the conventional example (tn <tQ).

  By using the dark current signal in the simple image processing that was acquired in the previous imaging, the simple image processing is performed in advance without waiting for the dark current signal accumulation, signal processing, and transfer to shorten the processing time. Can be achieved.

  The display image Qn is not equivalent when compared with the image QQ displayed in the conventional example, but the performance of the monitor (the monitor used in this embodiment has a resolution of 336 × 336, about 64 to 128 gradations) ), Or a simple image display, and an image that can be satisfactorily satisfied in view of the fact that the examination and diagnosis are not performed.

  When the simple image processing is completed in the control PC 2, the S signal image data and the F signal image data stored in the frame memory 106 are transferred to the control PC 2 at an arbitrary transfer rate, and the control PC 2 accepts the transfer of the S signal and the F signal. ,Store.

  Next, in this embodiment, since the capacity of the frame memory 106 is one frame, the transfer of the S signal is started before the F signal is written to the frame memory. However, when the capacity of the frame memory is two frames or more. Does not specify the order of transfer to the control PC. In addition, since the transfer rate is also provided with the frame memory, it can be made slower than the signal reading rate.

  Optimal image processing (main image processing) for performing inspection and diagnosis by subtracting the image data Fn for the F signal from the image data Sn for the S signal without thinning transferred from the frame memory 106 and performing dark current correction. ) And the result is stored in the data storage device 22, and the captured image file can be displayed on the monitor 20 and printed on the printer 21 as necessary.

  As described above, according to the radiation imaging apparatus according to the present embodiment, by providing a memory for storing frame image data, the transfer rate of image data to the display control unit is higher than the signal reading rate of the image sensor. It becomes possible to slow down.

  In synchronization with the storage of the frame image data, the selector circuit performs the thinning control of the image data, and the display control displays the simple image display in a short time from the X-ray exposure based on the thinned-out image data. Enable. According to this embodiment, the time taken for about 3 to 4 seconds in the conventional example can be reduced to about 2 seconds.

<Embodiment 2>
Next, a second embodiment according to the present invention will be described with reference to FIG. In FIG. 3, the same components as those in the imaging sequence of Embodiment 1 in FIG. 2 are denoted by the same reference numerals, and detailed description of overlapping portions is omitted.

  In the present embodiment, dark current correction processing for obtaining the display image QF in the simplified image processing of FIG. 3C is different from the first embodiment and dark current correction. The dark current correction signal used in the present embodiment uses dark current image data FF stored in advance in the control PC 2. Accordingly, the dark current corrected display image QF is defined by the following expression obtained by subtracting the dark current correction signal FF from the image data SS thinned out and transferred from the frame memory 106.

Dark current corrected image data (QF) = SS-FF
This dark current image data FF is an average value obtained by averaging a plurality of times of dark current image data, and a dark current that can ignore random noise that the image sensor has by taking the average of a plurality of times. It becomes image data. Note that the dark current image data FF to be actually subtracted is converted into a value proportional to the dark current accumulated during the S signal accumulation time Pn. The image QF displayed here is not the same as the image QQ displayed in the conventional example, but it is an image that is sufficiently satisfactory considering the performance of the monitor and simple image display.

  As described above, similarly in the radiographic apparatus according to the present embodiment, the transfer rate of the image signal to the control PC 2 can be made slower than the signal readout rate of the two-dimensional image sensor, and the system design can be improved. The degree of freedom is increased, and a special and expensive communication circuit is not required.

  In addition, it is possible to significantly reduce the time taken from the exposure of X-rays to the simple image display.

  As described above, in the radiation imaging apparatus according to the present embodiment as well, by providing a memory for storing frame image data, the transfer rate of image data to the display control unit is higher than the signal reading rate of the image sensor. It becomes possible to slow down.

  In synchronization with the storage of the frame image data, the selector circuit performs the thinning control of the image data, and the display control displays the simple image display in a short time from the X-ray exposure based on the thinned-out image data. Enable.

<Embodiment 3>
Next, a third embodiment according to the present invention will be described with reference to FIG. 4, the same components as those in the imaging sequence of the first embodiment in FIG. 2 are denoted by the same reference numerals, and detailed description of overlapping portions is omitted.

  As shown in FIG. 4C, the present embodiment is different from the first and second embodiments in that the simple image processing is performed twice in the operation of the control PC2.

  In the simple image processing 1, as in the first embodiment, the dark current correction is performed using the thinned image data SS and the dark current image data Fn-1 acquired in the previous shooting. Here, the display image displayed on the monitor as a result of the simple image processing 1 is Qn, which is defined by the following equation.

Dark-current corrected image data (Qn) = SS−Fn−1
The image Qn displayed here is the same as the image displayed in the first embodiment, and the time tn from the X-ray exposure to the image display is also the same.

  After the simple image processing, the transfer of the S signal and the F signal for the main image processing is accepted from the frame memory 106, and the second simple image processing 2 starts after the F signal transfer. In the dark current correction performed in the simple image processing 2, dark current correction is performed using the image data Sn based on the S signal and the image data Fn based on the F signal transferred from the frame memory 106. Image data Rn subjected to this dark current correction is defined by the following equation.

Dark current corrected image data (Rn) = Sn−Fn
The image Rn displayed here is based on the S signal that has not been thinned out, and is a higher quality image than the first simple image processing 1.

  According to the radiation imaging apparatus of the present embodiment, the display from the X-ray exposure to the image display is shortened by the first process out of the two simple image processes, and the quality of the simple image is displayed by the second display. It is possible to display high-quality without dropping the image.

Effect of the invention

  As described above, according to the radiation imaging apparatus of the present invention, by providing the memory for storing the frame image data, the transfer rate of the image data to the display control unit is slower than the signal reading rate of the image sensor. It becomes possible to do.

  In synchronization with the storage of the frame image data, the selector circuit performs the thinning control of the image data, and the display control displays the simple image display in a short time from the X-ray exposure based on the thinned-out image data. Enable.

  It is a block diagram explaining the structure of the radiography apparatus concerning embodiment of this invention.   It is a figure explaining the imaging | photography sequence of the radiography apparatus concerning the 1st Embodiment of this invention.   It is a figure explaining the imaging | photography sequence of the radiography apparatus concerning the 2nd Embodiment of this invention.   It is a figure explaining the imaging | photography sequence of the radiography apparatus concerning the 3rd Embodiment of this invention.   It is a block diagram explaining a prior art example structure.   It is a figure which shows the imaging | photography sequence in a prior art example.

1 Sensor unit 2 Control PC
101 Two-dimensional imaging device 102 Amplifier circuit 103 A / D converter 104 Line memory 105 Multiplex IC
106 Frame memory 107 Communication IC
108 Pulse generator 109 MPU
110 selector

Claims (14)

A digital radiation imaging apparatus that communicates with an external apparatus that includes an image processing unit that performs image processing on image data and a display control unit that displays the image processed image data on a display unit,
A two-dimensional imaging device that accumulates charges in response to X-ray exposure; an amplifier that amplifies an electrical signal based on the accumulated charges; and an AD converter that converts the amplified electrical signal into digital data; an imaging means comprising a
Storage means for memorize an X-ray image data based on the digital data,
A generating means for generating image data obtained some data in thinning Kukoto of the X-ray image data stored in the storage means,
Transfers image data said generated in the external device, after the transfer, starts the transfer of the image data including the data other than the image data the generated, the transfers of the stored X-ray image data A transfer means for completing
A digital radiation imaging apparatus comprising:
The digital radiation imaging apparatus according to claim 1, wherein the transfer unit transfers dark current data corresponding to the X-ray image data after transferring image data including data other than the generated image data. apparatus.
Display on the display unit of size as the external device of said X-ray image data thinning rate at the time of generating the image data obtained some data in thinning Kukoto of said generating means said X-ray image data The digital radiation imaging apparatus according to claim 1, further comprising setting means for setting according to a size of the region.
4. The digital radiation imaging apparatus according to claim 1, wherein a transfer rate of image data by the transfer unit is slower than a read rate for reading a charge signal from the imaging unit. 5.
A two-dimensional imaging device that accumulates charges in response to X-ray exposure; an amplifier that amplifies an electrical signal based on the accumulated charges; and an AD converter that converts the amplified electrical signal into digital data; An information processing apparatus connected to a digital radiation imaging apparatus for obtaining X-ray image data by an imaging means comprising :
Acquisition means for acquiring image data from the digital radiation imaging apparatus;
Display control means for displaying the image data acquired by the acquisition means on a display unit;
After acquired by the acquisition unit image data generated by thinning Kukoto part of the data of the X-ray image data captured from the digital radiation imaging apparatus in the digital radiation imaging apparatus, the display control means Accordingly, along with displaying the image data the generated on the display unit, and a control means for performing control of acquired by the acquisition unit image data including data other than the image data to which the generated in the digital radiation imaging apparatus,
An information processing apparatus comprising:
Information according to claim 5, further comprising a correction means for applying a dark current correction on the basis of the dark current data obtained image data generated some data in thinning Kukoto advance of the X-ray image data Processing equipment.
The information according to claim 6, wherein the correction unit uses dark current data obtained by taking an average of dark current data captured in advance before capturing the X-ray image data for the dark current correction. Processing equipment.
The control unit acquires image data including data other than the generated image data by the acquisition unit, and then acquires dark current data corresponding to the X-ray image data by the acquisition unit,
The correction means performs the dark current corrected based on the dark current data the obtained advance a portion of the data to the image data generated by thinning Kukoto of the X-ray image data, said generation The information processing apparatus according to claim 6, wherein dark current correction is performed on image data including data other than the processed image data based on dark current image data acquired by the acquisition unit.
The correction means displays the thinned image data subjected to the dark current correction, and then performs dark current correction on image data including data other than the generated image data,
The information processing apparatus according to claim 6, wherein the display control unit displays image data including data other than the generated image data that has been subjected to the dark current correction.
The control means starts acquisition of image data including data other than the generated image data in the digital radiation imaging apparatus after completion of dark current correction of the generated image data by the correction means. The information processing apparatus according to claim 6.
A radiation imaging apparatus having a digital radiation imaging apparatus that accumulates electric charges in response to X-ray exposure and obtains X-ray image data, and an information processing apparatus that displays an image captured by the digital radiation imaging apparatus on a display unit There,
The digital radiation imaging apparatus comprises:
A two-dimensional imaging device that accumulates charges in response to X-ray exposure; an amplifier that amplifies an electrical signal based on the accumulated charges; and an AD converter that converts the amplified electrical signal into digital data; an imaging means comprising a
Storage means for memorize an X-ray image data based on the digital data,
A generating means for generating image data obtained some data in thinning Kukoto of the X-ray image data stored in the storage means,
Transfers image data said generated in the information processing apparatus, after the transfer, starts the transfer of the image data including the data other than the image data the generated, the transfers of the stored X-ray image data And transfer means for completing
The information processing apparatus includes:
After acquiring the image data generated by thinning Kukoto part of the data of the X-ray image data from the digital radiation imaging apparatus, the display control unit, the display image data in which the generated on the display unit And a control means for performing control for acquiring image data including data other than the generated image data from the digital radiation imaging apparatus.
A method for controlling a digital radiation imaging apparatus that communicates with an external apparatus including an image processing unit that performs image processing on image data and a display control unit that displays the image data subjected to the image processing on a display unit,
A two-dimensional imaging device that accumulates charges in response to X- ray exposure; an amplifier that amplifies an electrical signal based on the accumulated charges; and an AD converter that converts the amplified electrical signal into digital data; Obtaining X-ray image data by an imaging means comprising:
Storing X-ray image data based on the digital data in a storage means;
A step wherein a portion of the data of the X-ray image data stored in the storage means to generate image data obtained by thinning Kukoto, decimating transfers the image data the generated to the external device,
After completion of the decimation transfer, the steps to complete the transfer begins of the image data including the data other than the image data the generated, transferred the X-ray image data the storage,
A control method for a digital radiation imaging apparatus, comprising:
A two-dimensional imaging device that accumulates charges in response to X-ray exposure; an amplifier that amplifies an electrical signal based on the accumulated charges; and an AD converter that converts the amplified electrical signal into digital data; A method of controlling an information processing apparatus connected to a digital radiation imaging apparatus that obtains X-ray image data by an imaging means comprising :
Acquiring image data generated some data in thinning Kukoto of X-ray image data captured by the digital radiographic apparatus from said digital radiographic imaging apparatus,
Displaying the image data on a display unit in response to the acquisition;
After acquiring the image data to which the generated, acquiring image data including data other than the image data to which the generated in the digital radiographic apparatus from said digital radiographic imaging apparatus,
A method for controlling an information processing apparatus, comprising:
A method for controlling a radiation imaging apparatus, comprising: a digital radiation imaging apparatus; and an information processing apparatus that acquires and displays an image from the digital radiation imaging apparatus,
The digital radiation imaging apparatus, and a two-dimensional imaging device for storing charge according to X-ray exposure, and an amplifier for amplifying an electric signal based on the accumulated charge, the electrical signal the amplified into digital data Obtaining X-ray image data by imaging means comprising: an AD converter for converting ;
Storing the X-ray image data in storage means of the digital radiation imaging apparatus;
The digital radiation imaging apparatus generates image data obtained some data in thinning Kukoto of X-ray image data stored in the storage means, decimating transfers the image data to the information processing apparatus Steps,
Displaying the thinned and transferred image data on a display unit of the information processing apparatus;
A step wherein the digital radiation imaging apparatus, for transferring the rear end to the thinning transfer, the image data including the data other than the image data the generated to the information processing apparatus,
A step of displaying the images data to which the transferred to the display unit of the information processing apparatus,
A control method for a radiation imaging apparatus, comprising:

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