JP3556029B2 - X-ray imaging device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an X-ray imaging apparatus using an X-ray detector including a plurality of X-ray detection elements that accumulate detected X-rays as electric charges.
[0002]
[Prior art]
The X-ray imaging apparatus irradiates a subject with X-rays, detects X-rays transmitted through the subject with an X-ray detector, and captures an image of the transmitted X-rays.
In recent years, as an X-ray imaging apparatus, portability of a screen film system or an imaging plate, high resolution characteristics of a film / screen system, and I.D. I. -An X-ray semiconductor flat panel detector using a TFT (thin film transistor) having a real-time property of a TV system as a switching gate has been developed.
[0003]
This X-ray semiconductor flat panel detector reads and outputs (outputs) a phosphor that converts X-rays into light, a photodiode that converts the light into charges, a capacitor that stores charges, and a charge on a flat detection surface. The photodiodes (and capacitors and TFTs) are two-dimensionally (planarly) arranged in an array.
[0004]
That is, as shown in FIG. 8, a gate electrode 102 is formed in a plurality of TFT regions on a support 101, and a SiNx layer 103 is formed thereon. On the SiNx layer 103, an a-Si layer 104, a drain electrode 105, and a source electrode 106 are formed in the TFT region. The drain electrode 105 and the source electrode 106 are connected via the a-Si layer 104 so that they do not come into direct contact with each other.
[0005]
Further, n + a · Si layers 107 and 108 are formed in gaps between the drain electrode 105 and the source electrode 106 and the a · Si layer 104.
Thus, a TFT is formed in the TFT region.
[0006]
On the other hand, the SiNx layer 103 and the source electrode 106 are formed in a plurality of PD regions on the support 101, and a photodiode having a pin structure including an n + layer 109, an i layer 110, and a p + layer 111 thereon. Is formed.
[0007]
A first polyimide resin layer 112 is formed on the TFT, and a transparent electrode 113 is formed on the photodiode. On the first polyimide resin layer 112, a metal electrode 114 connecting between the transparent electrodes 113 of the photodiode is formed. The metal electrode 114 also has a function of preventing light from entering the TFT.
[0008]
A second polyimide resin layer 115 is formed on the transparent electrode 113 and the metal electrode 114. On this second polyimide resin layer 115, a transparent protective film 116, a phosphor 117, and a light reflection layer 118 are formed.
[0009]
The photodiode and the TFT are connected in a circuit as shown in FIG. The photodiode 121 is connected in parallel with a capacitor (hereinafter referred to as a storage capacitor) 122, and a connection point between the anode terminal of the photodiode 121 and the storage capacitor 122 is connected to a reverse bias power supply (−Vn). A connection point between the cathode terminal of the photodiode 121 and the storage capacitor 122 is connected to a source terminal (the source electrode 106) of the TFT 123.
As the capacitor described here (for storage), the capacitance of the photodiode 121 may be used. If the capacitance of the photodiode 121 is insufficient, an additional capacitance may be used. May be added.
[0010]
As described later, the gate terminal of the TFT 123 is connected to a gate drive line, and the drain terminal is connected to a data signal line.
Thus, one X-ray detecting element is formed, and the X-ray detecting elements are two-dimensionally arranged to form an X-ray semiconductor flat panel detector.
[0011]
FIG. 10 is a circuit diagram showing a main configuration of the X-ray semiconductor flat panel detector.
The X-ray semiconductor flat panel detector includes an X-ray detection element 124 (the TFT 123 may be included in the X-ray detection element) including the photodiode 121 and the capacitor 122, and arranges the X-ray detection element 124 in rows and lines. Are arranged two-dimensionally.
[0012]
Further, the gate terminal of the TFT 123 is commonly connected as a gate drive line for each line, and is connected to each line output terminal of the gate driver 125. The drain terminal of the TFT 124 is commonly connected as a data signal line for each column, and includes a read-out amplifier (Read-out Amplifier), a capacitor (hereinafter referred to as a capacitor for a time constant), and a reset switch (not shown). ) Is connected to each input terminal of the multiplexer 127.
[0013]
From each line output terminal of the gate driver 125, a pulse-like control signal is sequentially output in time sequence, and the TFT 123 on the same line is simultaneously turned on by the pulse-like control signal, The TFTs 123 on different lines are turned on so that they do not overlap in time sequence.
[0014]
The multiplexer 127 takes in the signals input to the respective input terminals one by one in time series in one pulse output from the respective line output terminals of the gate driver 125, and outputs the signals from the output terminals. It is supposed to.
[0015]
Therefore, when the TFT 123 of one line is simultaneously turned on by the pulse-like control signal output from each line output terminal of the gate driver 125, the electric charge accumulated in the accumulation capacitor 122 is output through the TFT 123, This electric charge is converted into a voltage via an integrating circuit 126, and is sequentially output one by one (one pixel per line) by the multiplexer 127. When reading of one line is completed in this way, reading of the next line is started.
[0016]
That is, like a scanning line of a television, a detection signal is read one by one (one pixel at a time) in order for each X-ray detection element 124 for each line, and output as image data (video signal) for one screen. It has become. Note that a period in which one screen of image data is read from the X-ray semiconductor flat panel detector is one frame.
[0017]
In the X-ray semiconductor flat panel detector having such a configuration, the X-ray transmitted through the subject from above is transmitted through the light reflection layer 118 and is incident on the phosphor 117. At this time, the visible light incident from above is reflected by the light reflection layer 118 and is not incident on the phosphor 117.
[0018]
The energy of the incident X-ray is converted into light energy (visible light) by the phosphor 117, and this visible light passes through the transparent protective film 116 and the second polyimide resin layer 115, and further passes through the transparent electrode 113. The light is received by the photodiode 121 (the n + layer 109, the i layer 110, and the p + layer 111) which has high sensitivity.
[0019]
The energy of the incident X-rays is converted by the photodiode 121 into a charge amount proportional to the intensity of the light, and is stored in the storage capacitor 122. As described above, the accumulated electric charges are read out by the TFT 123 through the data signal lines in units of pixels for each line (for each column). The read signal is proportional to the intensity of the X-ray, and an X-ray image can be reproduced by reconstructing the signal read in pixel units.
[0020]
Further, there are the following two methods for setting the timing of X-ray irradiation and reading of imaging data from the X-ray semiconductor flat panel detector.
In the first method, as shown in FIG. 11 (a), in the case of one-shot imaging (single-shot imaging), the reading from the X-ray semiconductor flat panel detector (detector) is completely stopped without being periodically performed. The X-ray semiconductor flat panel detector is driven to read the image data at the timing when the X-ray irradiation is completed.
[0021]
Strictly speaking, the data line output is a signal in which the accumulated charge for each pixel (X-ray detection element) is output through the integration circuit 126 and is sequentially output in a time-series manner. For simplicity, these signals are shown consecutively.
[0022]
In the second method, as shown in FIG. 11B, a blanking period for stopping the driving of the X-ray semiconductor flat panel detector is provided to stop the X-ray semiconductor flat panel detector periodically like a normal video signal. In this case, X-ray irradiation is performed during the blanking period.
[0023]
[Problems to be solved by the invention]
In the first method, X-ray irradiation can be performed at an arbitrary timing. However, there is a problem that it is necessary to control the drive timing of the X-ray semiconductor flat panel detector in accordance with the X-ray irradiation timing. Was.
[0024]
In the second method, it is not necessary to control the drive timing of the X-ray semiconductor flat panel detector, but it is necessary to control the X-ray emission timing in accordance with the blanking period of the drive timing of the X-ray semiconductor flat panel detector. In addition, there is a problem that the X-ray irradiation time is limited to the blanking period.
[0025]
Therefore, the present invention provides an X-ray imaging apparatus that can perform X-ray irradiation at an arbitrary timing for a desired time while continuously driving an X-ray detector, and can obtain an accurate X-ray image. The purpose is to do.
[0026]
[Means for Solving the Problems]
A first aspect of the present invention providesX-ray emitting means for emitting X-rays, X-ray detecting means for detecting incident X-rays and outputting imaging data based on the detected X-rays, and X-ray emitting means for the X-ray emitting means. From the frame corresponding to the start of irradiation to the frame following the frame corresponding to the end of X-ray exposureDuring the periodX-ray detecting meansFromAdd output imaging datado itReconstructing means for reconstructing an X-ray image.
A second aspect of the present invention providesAn X-ray irradiating unit configured to irradiate X-rays; an X-ray detector including a plurality of X-ray detection elements configured to detect incident X-rays and accumulate the detected X-rays as electric charges; Reading means for reading out the electric charge accumulated in the line detecting element as electric charge data, and a period from the frame corresponding to the start of X-ray irradiation by the X-ray irradiation means to the frame next to the frame corresponding to the end of X-ray irradiation. And reconstructing means for reconstructing an X-ray image by adding charge data read from the plurality of X-ray detection elements for each of the X-ray detection elements.
A third aspect of the present invention provides:X-ray emitting means for emitting X-rays, X-ray detecting means for detecting incident X-rays and outputting imaging data based on the detected X-rays, and X-ray emitting means for the X-ray emitting means. During the period from the frame following the frame corresponding to the start of the irradiation to the frame corresponding to the end of the X-ray exposure, the output of the imaging data from the X-ray detection unit is stopped, and the imaging data is stored in the X-ray detection unit. The stopping means for generating accumulated data, and the X-ray detecting means in the next frame after the frame corresponding to the start of the X-ray irradiation and the frame corresponding to the end of the X-ray irradiation of the X-ray emitting means, Reconstructing means for reconstructing an X-ray image based on added data obtained by adding the output imaging data and the accumulated data.
A fourth aspect of the present invention provides:An X-ray irradiating unit configured to irradiate X-rays; an X-ray detector including a plurality of X-ray detection elements configured to detect incident X-rays and accumulate the detected X-rays as electric charges; Reading means for reading out the electric charge accumulated in the X-ray detecting element as electric charge data, and a period from the frame following the frame corresponding to the start of the X-ray irradiation by the X-ray irradiation means to the frame corresponding to the end of the X-ray irradiation. Stopping the reading by the reading means and accumulating the imaging data for each of the X-ray detection elements, thereby providing a stopping means for generating the accumulated data, which corresponds to the start of the X-ray irradiation by the X-ray irradiation means. Addition data obtained by adding the charge data read by the reading means and the accumulated data for each X-ray detection element in a frame and a frame next to a frame corresponding to the end of X-ray exposure Based on comprises a reconstruction means for reconstructing an X-ray image.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram showing a main configuration of an X-ray imaging apparatus to which the present invention is applied until an X-ray image is reconstructed. The other configuration of the X-ray imaging apparatus is the same as that of a general X-ray imaging apparatus, and a description thereof will not be repeated.
[0031]
Reference numeral 1 denotes an X-ray semiconductor flat panel detector (a plurality of X-ray detecting elements composed of a photodiode, a capacitor, and a TFT described in the related art are arranged two-dimensionally on a two-dimensional plane, and X-rays are converted to light. An X-ray detector using a phosphor provided for conversion, see FIGS. 8 to 10). The analog imaging signal (serial signal) for one screen (one frame) output from the X-ray detector 1 is input to the A / D converter 2. The A / D converter 2 converts the image signal into digital image data, and stores the image data in a first frame memory 4-1, a second frame memory 4-2, and a third frame memory via a memory control unit 3. Are supplied to and stored in a memory section composed of n frame memories of the memories 4-3,....
[0032]
The memory control unit 3 changes a frame memory as a supply destination of digital imaging data based on an X-ray signal indicating whether or not X-ray irradiation is performed. As a method of generating the X-ray signal, although not shown, for example, there is a method described below.
[0033]
The first method is a method of directly connecting to an X-ray tube device that generates X-rays and irradiates the object (subject), and inputs an X-ray irradiation drive signal as an X-ray signal.
The second method is a method in which an X-ray sensor made of a material that hardly absorbs X-rays is installed on an X-ray incident surface of an X-ray detector, and an X-ray detection signal from the X-ray sensor is used as an X-ray signal. . For example, there are ABC (Auto Brightness Control) and AEC (Auto Exboger Control).
[0034]
The third method is to install an X-ray sensor for detecting X-rays on the back surface of the X-ray detector (the side opposite to the X-ray incident surface) and detect X-rays leaking to the back surface of the X-ray detector. This is a method of converting an X-ray detection signal from the X-ray sensor into an X-ray signal.
In a fourth method, one of the X-ray detection elements (one pixel, one on the edge of the reading range) of the X-ray semiconductor flat panel detector of the X-ray detector is used as an X-ray sensor. Is used as the X-ray signal.
[0035]
A fifth method is to use a plurality of X-ray detecting elements (for example, one line or one line) of the X-ray semiconductor flat panel detector of the X-ray detector as an X-ray sensor, and to perform detection from these X-ray detecting elements. This is a method of generating an X-ray signal from a signal.
The sixth method is a method in which an ammeter for sensing a current flowing through an X-ray tube (a driving current for generating X-rays) is installed, and an output signal from the ammeter is used as an X-ray signal.
[0036]
In the first embodiment and the following embodiments, the method of generating the X-ray signal may be any of the above, and another method may be used.
[0037]
When the X-ray signal obtained by any of the above methods is a signal indicating that X-ray irradiation has not been performed, the memory control unit 3 controls the input digital signal from the A / D converter 2. The imaging data is supplied to the first frame memory 4-1. In the first frame memory 4-1, the supplied imaging data is sequentially overwritten and stored.
[0038]
When the X-ray signal becomes a signal indicating that X-ray irradiation is performed, the supply destination of the imaging data output from the A / D converter 12 is set for each frame from the next frame after the current frame. The frame memory is sequentially changed to the second frame memory 4-2, the third frame memory 4-3, and so on.
[0039]
Then, when the X-ray signal changes from a signal indicating that X-ray irradiation has been performed to a signal indicating that X-ray irradiation has not been performed, that is, when the X-ray irradiation ends, the X-ray irradiation ends. The above-described change of the supply destination frame memory is continued until the next frame of the frame, and the supply destination of the imaging data of the next frame is returned to the first frame memory 4-1 again.
[0040]
Here, for example, the frame memory in which the imaging data of the frame next to the frame at the end of the X-ray exposure is stored is referred to as an x-th frame memory.
When the writing of the imaging data into the x-th frame memory is completed, the X-ray image reconstruction from the imaging data stored in the first frame memory 4-1 to the imaging data stored in the x-th frame memory is completed. The addition and averaging process are performed for each pixel by the unit 5 and reconstructed as one X-ray image. The reconstructed X-ray image is output to an output device such as a display or a storage device such as a hard disk.
[0041]
In the first embodiment having such a configuration, X-ray imaging is performed by performing X-ray irradiation at an arbitrary timing in a state where the X-ray detector 1 is driven normally and continuously. For example, a case where X-ray irradiation shorter than one frame is performed based on the timing shown in FIG. 2 will be described.
[0042]
At the time point t1 when the X-ray irradiation is started, one frame of digital imaging data A1 output from the X-ray detector 1 via the A / D converter 2 is transmitted to the first frame via the memory control unit 3. It is stored in the memory 4-1.
Even at the time point t2 when the X-ray irradiation ends, the digital imaging data output from the X-ray detector 1 via the A / D converter 2 is the imaging data A1 of the same frame as described above. The data is continuously stored in the first frame memory 4-1.
[0043]
The digital imaging data A2 of the frame next to the frame at the time point t2 at which the X-ray exposure ends is stored in the second frame memory 4-2 via the memory control unit 3.
[0044]
When the writing of the image data A2 to the second frame memory 4-2 is completed, the X-ray image reconstructing unit 5 causes the image data of the first frame memory 4-1 and the second frame memory 4-2 to be read. And X-ray image data are averaged for each pixel to reconstruct one X-ray image. In the reconstruction of the X-ray image, it is not necessary to perform the averaging process only by adding. This is the same in the following embodiments.
[0045]
Further, a case where X-ray irradiation longer than one frame is performed based on the timing shown in FIG. 3 will be described.
At time t3 when X-ray irradiation is started, one frame of digital imaging data B1 output from the X-ray detector 1 via the A / D converter 2 is transmitted to the first frame via the memory control unit 3. It is stored in the memory 4-1.
[0046]
Since the X-ray irradiation is being performed on the imaging data B2 of the next frame and the subsequent imaging data B3, B4, and B5, the imaging data B2 is sequentially stored in the second frame memory 4-2 via the memory control unit 3. , The imaging data B3 is stored in the third frame memory 4-3, the imaging data B4 is stored in the fourth frame memory, and the imaging data B5 is stored in the fifth frame memory.
[0047]
In the next frame, the X-ray irradiation ends (time point t4), so the imaging data B6 at that time point t4 is also stored in the sixth frame memory, and further, at the time point t4 when the X-ray irradiation ends. The imaging data B7 of the frame next to the frame is also stored in the next seventh frame memory.
[0048]
When the writing of the imaging data B7 of the frame next to the frame at the time point t4 when the X-ray exposure ends in the seventh frame memory, the X-ray image reconstructing unit 5 causes the first frame memory 4-1. The X-ray image is reconstructed by adding and averaging the image data of the seventh frame memory to the image data of the seventh frame memory for each pixel (the averaging process is not required).
[0049]
As described above, according to the first embodiment, the plurality of frame memories 4-1, 4-2,... A memory control unit 3 for selecting and storing image data of each frame up to a frame next to the frame at the end point by selecting a different frame memory, and performing an averaging process on the image data of each frame memory for each pixel, and By providing the X-ray image reconstructing unit 5 for reconstructing an image, it is possible to perform X-ray irradiation at an arbitrary timing and for a desired time while the X-ray detector 1 is continuously driven. It is possible to obtain an accurate X-ray image with improved S / N by utilizing the effective imaging data without waste.
[0050]
A second embodiment of the present invention will be described with reference to FIG.
FIG. 4 is a block diagram showing a main part configuration of an X-ray imaging apparatus to which the present invention is applied until an X-ray image is reconstructed. The other configuration of the X-ray imaging apparatus is the same as that of a general X-ray imaging apparatus, and a description thereof will not be repeated.
[0051]
The analog imaging signal (serial signal) for one screen (one frame) output from the X-ray detector 11 is input to the A / D converter 12. The A / D converter 12 converts the image signal into digital image data and supplies it to a main memory 14 via an adder 13. The main memory 14 overwrites the sequentially supplied image data. It is memorized.
[0052]
The adder 13 reads the imaging data stored in the main memory 14 using an X-ray signal indicating whether or not X-ray irradiation has been performed, and reads the imaging data supplied from the A / D converter 12. Is added for each pixel, and the added image data is supplied to the main memory 14 again. In the main memory 14, the sequentially supplied image data is overwritten and stored.
[0053]
That is, when the X-ray signal is a signal indicating that X-ray irradiation is not performed, the imaging data output from the A / D converter 12 is not read out from the main memory 14 and the imaging data is output as it is. The image data is supplied to the main memory 14, and the main memory 14 overwrites and stores the sequentially supplied image data. When the X-ray signal becomes a signal indicating that X-ray irradiation is performed, the imaging data is read from the main memory 14 and added to the imaging data supplied from the A / D converter 12 for each pixel. It is supplied to the main memory 14 again, and the main memory 14 overwrites and stores the added image data.
[0054]
Then, when the X-ray signal changes from a signal indicating that X-ray irradiation has been performed to a signal indicating that X-ray irradiation has not been performed, that is, when X-ray irradiation ends, the frame at the end of X-ray irradiation The imaging data is read from the main memory 14 until the next frame, and is added to the imaging data supplied from the A / D converter 12 for each pixel, and is again supplied to the main memory 14. At 14, the supplied imaging signal is overwritten and stored.
[0055]
When the writing of the imaging data of the frame following the frame at the end of the X-ray exposure to the main memory 14 is completed, the imaging data stored in the main memory 14 is averaged by the X-ray image reconstructing unit 15. It is processed and reconstructed as one X-ray image. The reconstructed X-ray image is output to an output device such as a display or a storage device such as a hard disk.
[0056]
In the second embodiment having such a configuration, X-ray imaging is performed by performing X-ray irradiation at an arbitrary timing in a state where the X-ray detector 11 is driven normally and continuously. For example, a case where X-ray irradiation shorter than one frame is performed based on the timing shown in FIG. 2 will be described.
[0057]
At time t1 when X-ray irradiation is started, one frame of digital imaging data A1 output from the X-ray detector 11 via the A / D converter 12 is subjected to addition processing via the adder 13. And stored in the main memory 14 as it is.
Even at the time point t2 when the X-ray irradiation ends, the digital imaging data output from the X-ray detector 11 via the A / D converter 12 is the imaging data A1 of the same frame as described above. Stored in the memory 14.
[0058]
The digital imaging data A2 of the frame next to the frame at the time point t2 at which the X-ray exposure ends is added to the imaging data (A1) read from the main memory 14 by the adder 13 and stored in the main memory 14. You.
Then, when the writing of the imaging data obtained by adding the imaging data (A1) from the main memory 14 and the imaging data A2 to the main memory 14 is completed, the X-ray image reconstructing unit 15 performs an averaging process to obtain one image. Is reconstructed.
[0059]
Further, a case where X-ray irradiation longer than one frame is performed based on the timing shown in FIG. 3 will be described.
At time t3 when X-ray irradiation is started, one frame of digital imaging data B1 output from the X-ray detector 11 via the A / D converter 12 is subjected to addition processing via the adder 13. They are stored in the main memory 14 without any change.
[0060]
Since the X-ray irradiation is being performed on the imaging data B2 of the next frame and the imaging data B3, B4, and B5 thereafter, the imaging data B2 is sequentially stored in the main memory 14 by the adder 13. B1) and is stored in the main memory 14, the image data B3 is added to the image data (B1 + B2) stored in the main memory 14 and stored in the main memory 14, and the image data B4 is stored in the main memory. The image data (B1 + B2 + B3) is added to the image data (B1 + B2 + B3) and stored in the main memory 14, and the image data B5 is added to the image data (B1 + B2 + B3 + B4) stored in the main memory 14 and stored in the main memory 14.
[0061]
In the next frame, the X-ray irradiation ends (time point t4), so that the imaging data B6 at that time point t4 is also added to the imaging data (B1 +... + B5) stored in the main memory 14 and the main memory 14 is stored. Further, the image data B7 of the frame next to the frame at the time point t4 when the X-ray exposure ends is also added to the image data (B1 + ... + B6) stored in the main memory 14 and stored in the main memory 14. You.
[0062]
When the writing of the imaging data B7 of the frame next to the frame at the time point t4 when the X-ray exposure ends in the main memory 14, the X-ray image reconstructing unit 15 performs an averaging process to obtain one X-ray image. Is reconstructed.
[0063]
As described above, according to the second embodiment, the main memory 14 and the frame from the start time of the X-ray exposure to the frame next to the frame at the end time of the X-ray exposure are based on the X-ray signal. An adder 13 for sequentially adding the imaging data and storing it in a main memory 14; and an X-ray image reconstructing unit 15 for reconstructing an X-ray image by averaging the cumulatively added imaging data stored in the main memory 14. Thus, the same effect as in the first embodiment can be obtained. Further, only one main memory 14 is required, and the X-ray image reconstruction unit only needs to perform the averaging process. Therefore, the memory capacity can be reduced and the processing load on the X-ray image reconstruction unit 15 can be reduced. There is an effect that can be.
[0064]
A third embodiment of the present invention will be described with reference to FIG.
FIG. 5 is a block diagram showing a main configuration of an X-ray imaging apparatus to which the present invention is applied until an X-ray image is reconstructed. The other configuration of the X-ray imaging apparatus is the same as that of a general X-ray imaging apparatus, and a description thereof will not be repeated.
[0065]
The analog image signal (serial signal) for one screen (one frame) output from the X-ray detector 21 is input to the A / D converter 22. The A / D converter 22 converts the image signal into digital image data, and supplies the digital image data to the first frame memory 24-1 or the second frame memory 24-2 via the memory control unit 23 for storage. Is done.
[0066]
The gate driver 21-1 that controls the driving of reading the image signal in the X-ray detector 21 is a signal indicating that the X-ray signal is not irradiated from the signal indicating that the X-ray signal is not irradiated. When the X-ray irradiation is started, the driving of reading the image signal of the X-ray detector 21 is stopped from the frame next to the frame at the start, and the X-ray signal is irradiated. From the signal indicating that the X-ray exposure has not been completed, that is, when the X-ray exposure has been completed, the imaging signal of the X-ray detector 21 from the next frame after the frame at the end of the X-ray exposure has been completed. The reading drive is restarted.
[0067]
During the period during which the driving of reading the image signal of the X-ray detector 21 by the gate driver 21-1 is stopped, the accumulation of electric charge according to the dose of X-rays is continued by each X-ray detection element. Is being done.
[0068]
The memory control unit 23 changes the frame memory to which the digital imaging data is supplied based on the X-ray signal. That is, when the X-ray signal is a signal indicating that X-ray irradiation is not performed, the memory control unit 23 converts the input digital imaging data from the A / D converter 22 into the first frame memory. The first frame memory 24-1 sequentially overwrites and stores the supplied image data.
[0069]
When the X-ray signal becomes a signal indicating that X-ray irradiation is performed from a signal indicating that X-ray irradiation is not performed, that is, at the time of starting X-ray irradiation, the X-ray signal starts from the next frame after the start frame. The imaging data output from the A / D converter 22 is supplied to the second frame memory 24-2, and the second frame memory 24-2 stores the sequentially supplied imaging data overwritten.
[0070]
Further, when the X-ray signal changes from a signal indicating that X-ray irradiation has been performed to a signal indicating that X-ray irradiation has not been performed, that is, at the end of X-ray irradiation, the frame following the frame at the end of this X-ray irradiation The image data is supplied to the second frame memory 24-2, and the image data of the next frame is supplied to the first frame memory 24-1. The supplied imaging data is overwritten and stored.
[0071]
When the writing of the imaging data into the second frame memory 24-2 is completed, the imaging data stored in the first frame memory 24-1 and the second frame memory 24-2 is re-exposed to the X-ray image. The composition unit 25 adds and averages the values for each pixel, and is reconstructed as one X-ray image. The reconstructed X-ray image is output to an output device such as a display or a storage device such as a hard disk.
[0072]
In the third embodiment having such a configuration, X-ray imaging is performed by performing X-ray irradiation at an arbitrary timing in a state where the X-ray detector 1 is driven normally and continuously. For example, a case in which X-ray irradiation longer than one frame is performed based on the timing shown in FIG. 6 will be described. Note that the X-ray irradiation shorter than one frame is the same as in the first embodiment described above, and the description thereof will be omitted.
[0073]
At time t5 when the X-ray irradiation is started, one frame of digital imaging data C1 output from the X-ray detector 21 via the A / D converter 22 is transmitted to the first frame via the memory control unit 23. Stored in the memory 24-1.
At this time, the driving of reading the image signal of the X-ray detector 21 is stopped by the gate driver 21-1 from the frame next to the time point t5. In this embodiment, when the driving of the X-ray detector 21 is stopped, the driving of the A / D converter 22 is also stopped, and when the driving of the X-ray detector 21 is restarted, the driving of the A / D converter 22 is stopped. Driving is restarted synchronously.
[0074]
At the time point t6 when the X-ray irradiation ends, the driving of the X-ray detector 21 is restarted by the gate driver 21-1 from the frame next to the frame at the time point t6. At the time of the restart, the digital imaging data C2 of one frame output from the X-ray detector 21 via the A / D converter 22 is stored in the second frame memory 24-2 via the memory control unit 23. Is done.
[0075]
When the writing of the imaging data C2 of the frame next to the frame at the time point t6 at which the X-ray exposure ends in the second frame memory 24-2 ends, the X-ray image reconstructing unit 25 causes the first frame memory The imaging data stored in the 24-1 and the second frame memories 24-2 are added up for each pixel and averaged to reconstruct one X-ray image.
[0076]
As described above, according to the third embodiment, when the X-ray irradiation is started based on the X-ray signal, the driving of reading of the X-ray detector 21 is stopped, and when the X-ray irradiation ends, the reading is stopped. A gate driver 21-1 for restarting the driving of reading of the X-ray detector 21 from the frame next to the frame at the time point, the first frame memory 24-1 and the second frame memory 24-2, Based on this, the imaging data of the frame at the start of the X-ray irradiation is stored in the first frame memory 24-1 and the imaging data of the frame next to the frame at the end of the X-ray irradiation is stored in the second frame memory. X-2 for reconstructing an X-ray image by adding the image data of the first frame memory 24-1 and the image data of the second frame memory 24-2 for each pixel and averaging the same for each pixel A line image reconstruction unit 25 is provided. It makes while continuously driven X-ray detector 1, it is possible to perform the desired time X-ray exposure at any time, it is possible to obtain accurate X-ray images.
[0077]
In addition, in the third embodiment, an imaging signal necessary for reconstructing an X-ray image can be obtained from the X-ray detector 21 twice, so that noise due to the reading can be reduced. Therefore, an X-ray image with less noise can be obtained.
Further, since the number of times of addition processing is reduced by accumulating charges by the X-ray detection element, the processing load on the X-ray image reconstruction unit 25 and the like can be reduced.
[0078]
A fourth embodiment of the present invention will be described with reference to FIG.
FIG. 7 is a block diagram showing a main configuration of an X-ray imaging apparatus to which the present invention is applied until an X-ray image is reconstructed. The other configuration of the X-ray imaging apparatus is the same as that of a general X-ray imaging apparatus, and a description thereof will not be repeated.
[0079]
The analog image signal (serial signal) for one screen (one frame) output from the X-ray detector 31 is input to the A / D converter 32. The image signal is converted into digital image data by the A / D converter 32, and the first frame memory 34-1, the second frame memory 34-2, and the third frame are transmitted via the memory control unit 33. Are supplied to and stored in a memory unit including a plurality of frame memories of the memories 34-3,.
[0080]
The gate driver 31-1 that controls the driving of reading the image signal in the X-ray detector 31 performs X-ray emission from the signal indicating that the X-ray signal from the mode determination unit 35 does not emit X-ray. Is stopped, the driving of reading of the imaging signal of the X-ray detector 31 is stopped from the frame next to the current frame, and the X-ray signal from the mode determination unit 35 is irradiated with X-rays. When a signal indicating that X-ray irradiation is not performed from a signal indicating that the X-ray detector 31 is present, the driving of reading the imaging signal of the X-ray detector 31 is restarted from the frame next to the current frame.
[0081]
Note that during the period in which the driving of reading the image signal of the X-ray detector 31 by the gate driver 31-1 is stopped, the accumulation of electric charge according to the dose of X-rays is continued by each X-ray detection element. Is being done.
[0082]
When the driving of reading the image signal of the X-ray detector 31 is stopped, the driving of the A / D converter 32 is also stopped. When the driving of reading of the image signal of the X-ray detector 31 is restarted, A The driving of the / D converter 32 also restarts in synchronization.
[0083]
The memory control unit 33 changes the frame memory to which the digital imaging data is supplied based on the X-ray signal from the mode determination unit 35. That is, when the X-ray signal from the mode determination unit 35 is a signal indicating that X-ray irradiation is not performed, the memory control unit 33 converts the input digital imaging data from the A / D converter 32 into The image data is supplied to the first frame memory 34-1. The first frame memory 34-1 sequentially stores the supplied image data by overwriting.
[0084]
When the X-ray signal from the mode determination unit 35 changes from a signal indicating that X-ray irradiation is not performed to a signal indicating that X-ray irradiation is performed, For each frame of imaging data output from the A / D converter 32, the frame memory of the supply destination is sequentially changed to the second frame memory 34-2, the third frame memory 34-3,... To go.
[0085]
When the X-ray signal from the mode determination unit 35 changes from a signal indicating that X-ray irradiation has been performed to a signal indicating that X-ray irradiation has not been performed, the imaging data of the frame next to the frame at this time is obtained. Up to this point, the change of the supply destination frame memory is continued, and the supply destination of the imaging data of the next frame is returned to the first frame memory 34-1 again.
[0086]
Here, for example, the frame memory in which the imaging data of the frame next to the frame at the end of the X-ray exposure is stored is referred to as an x-th frame memory.
When the writing of the imaging data to the x-th frame memory is completed, the X-ray image reproduction from the imaging data stored in the first frame memory 34-1 to the imaging data stored in the x-th frame memory is completed. The composition unit 36 adds and averages the values for each pixel, and is reconstructed as one X-ray image. The reconstructed X-ray image is output to an output device such as a display or a storage device such as a hard disk.
[0087]
The mode determination unit 35 is provided with a manual switch (not shown) for switching between the mode corresponding to the above-described first embodiment and the mode corresponding to the above-described third embodiment, or an X-ray amount to be used. An X-ray signal indicating whether or not X-ray irradiation is being performed is supplied to the memory control unit 33 only or to the memory control unit 33 based on a part to be imaged or the like, and the gate driver 31-1 is also supplied.
[0088]
In the fourth embodiment having such a configuration, a mode corresponding to the above-described first embodiment is set by the manual switch, or when an X-ray dose to be used is large, an image is taken when a part to be used is large. For example, the mode determination unit 35 supplies the X-ray signal only to the memory control unit 33.
Therefore, as in the first embodiment described above, the imaging data is stored in different frame memories for each frame from the frame at the start of X-ray exposure to the next frame after the frame at the end of X-ray exposure. The image data stored in each frame memory is added and averaged for each pixel, and one X-ray image is reconstructed.
[0089]
In addition, in the mode corresponding to the above-described second embodiment using the manual switch, or when the X-ray dose to be used is small, the mode determination unit 35 performs the X-ray The signal is supplied to the memory control unit 33 and also to the gate driver 31-1.
[0090]
Therefore, as in the above-described second embodiment, the imaging data of the frame at the start of the X-ray irradiation is stored in the first frame memory 34-1 and the X-ray irradiation ends from the next frame. Drive of the X-ray detector 31 and the A / D converter 32 is stopped until the X-ray detector 31 and the A / D converter 32 are driven. Is resumed, and the imaging data of the frame next to the frame at the end of the X-ray exposure is stored in the second frame memory 34-2. Then, the image data of the first frame memory 34-1 and the second frame memory 34-2 are added for each pixel and averaged to reconstruct one X-ray image.
[0091]
As described above, according to the fourth embodiment, the mode determination unit 35 for selecting and switching between the imaging processing method of the first embodiment and the imaging processing method of the second embodiment is provided. As a result, it is possible to perform an optimal imaging processing operation in accordance with the needs of the operator, the X-ray dose to be used, the application to be imaged, and the like, and as a result, improve the S / N as described above. The same effects as those of the third embodiment or effects similar to those of the above-described third embodiment for reducing noise can be obtained.
[0092]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to perform X-ray irradiation for a desired time at an arbitrary timing while continuously driving an X-ray detector, and to obtain an accurate X-ray image. An X-ray imaging device that can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a main part of an X-ray imaging apparatus according to a first embodiment of the present invention before reconstructing an X-ray image.
FIG. 2 is a diagram showing timings of X-ray irradiation for a shorter time than one frame and timings of an X-ray detector according to the first embodiment and the second embodiment.
FIG. 3 is a diagram showing timings of X-ray irradiation for a longer time than one frame and X-ray detectors according to the first embodiment and the second embodiment.
FIG. 4 is a block diagram showing a configuration of a main part of an X-ray imaging apparatus according to a second embodiment of the present invention until an X-ray image is reconstructed.
FIG. 5 is a block diagram showing a configuration of a main part of an X-ray imaging apparatus according to a third embodiment of the present invention before reconstructing an X-ray image.
FIG. 6 is a diagram showing timings of X-ray irradiation and an X-ray detector for a longer time than one frame according to the embodiment;
FIG. 7 is a block diagram showing a configuration of a main part of an X-ray imaging apparatus according to a fourth embodiment of the present invention until an X-ray image is reconstructed.
FIG. 8 is a cross-sectional view showing a main structure of an X-ray detection element included in the X-ray semiconductor flat panel detector.
FIG. 9 is a circuit diagram showing an X-ray detection element constituting the X-ray semiconductor flat panel detector.
FIG. 10 is a circuit diagram showing a main configuration of an X-ray semiconductor flat panel detector.
FIG. 11 is a diagram showing timings of X-ray irradiation and driving of an X-ray detector in a conventional example.
[Explanation of symbols]
1,11,21,31 ... X-ray detector,
2, 12, 22, 32 ... A / D converter,
3, 23, 33: memory control unit,
13 ... adder,
4-1, 4-2, 4-3, ..., 24-1, 24-2, 34-1, 34-2, 34-3, ... frame memory,
14 ... Main memory,
5, 15, 25, 36 ... X-ray image reconstruction unit,
35 ... mode determination unit.

Claims (4)

X-ray emitting means for emitting X-rays, X-ray detecting means for detecting incident X-rays and outputting imaging data based on the detected X-rays,
The imaging data output from the X-ray detection unit is added to the period from the frame corresponding to the start of the X-ray exposure of the X-ray exposure unit to the frame next to the frame corresponding to the end of the X-ray exposure, and X is added. Reconstructing means for reconstructing a line image;
An X-ray imaging apparatus comprising:   X-ray irradiating means for irradiating X-rays,
  An X-ray detector including a plurality of X-ray detection elements that detect incident X-rays and accumulate the detected X-rays as electric charges;
  Reading means for reading out the charge accumulated in the plurality of X-ray detection elements as charge data;
  The charge data read out from the plurality of X-ray detection elements during a period from a frame corresponding to the start of X-ray irradiation by the X-ray irradiation unit to a frame next to the frame corresponding to the end of X-ray irradiation is stored in the X-ray irradiation unit. Reconstructing means for reconstructing an X-ray image by adding for each detection element;
  An X-ray imaging apparatus comprising:   X-ray irradiating means for irradiating X-rays,
  X-ray detection means for detecting incident X-rays and outputting imaging data based on the detected X-rays;
  During the period from the frame next to the frame corresponding to the start of X-ray irradiation of the X-ray irradiation unit to the frame corresponding to the end of X-ray irradiation, the output of the imaging data from the X-ray detection unit is stopped, Stopping means for generating accumulated data by causing the X-ray detecting means to accumulate the imaging data;
  In the frame corresponding to the start of X-ray irradiation of the X-ray irradiation unit and the frame corresponding to the end of X-ray irradiation, the image data output by the X-ray detection unit and the accumulated data are added. Reconstructing means for reconstructing an X-ray image based on the addition data;
  An X-ray imaging apparatus comprising:   X-ray irradiating means for irradiating X-rays,
  An X-ray detector including a plurality of X-ray detection elements that detect incident X-rays and accumulate the detected X-rays as electric charges;
  Reading means for reading out the charge accumulated in the plurality of X-ray detection elements as charge data;
  During the period from the frame next to the frame corresponding to the start of X-ray irradiation of the X-ray irradiation unit to the frame corresponding to the end of X-ray irradiation, reading by the reading unit is stopped, and Stopping means for generating accumulated data by accumulating the imaging data;
  In the next frame after the frame corresponding to the start of the X-ray irradiation of the X-ray irradiation unit and the frame corresponding to the end of the X-ray irradiation, the charge data read by the reading unit and the accumulated data are detected by the X-ray detection. Reconstructing means for reconstructing an X-ray image based on addition data added for each element;
  An X-ray imaging apparatus comprising:

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