KR102467711B1 - X-ray detector and X-ray apparatus using the same - Google Patents

Abstract

The present invention includes a plurality of image pixels arranged in a matrix form along row lines and column lines and accumulating electric charges for generating an X-ray image signal in a main frame section during X-ray irradiation, among the plurality of image pixels Some are defined as function pixels that detect whether or not the X-ray is irradiated or detect the amount of radiation, and the plurality of image pixels including the function pixels are read out at a first frame rate during or after the main frame period and the functional pixels are read out at a second frame rate higher than the first frame rate in a waiting period before the X-ray irradiation and a sensing period before the main frame period after the start of the X-ray irradiation. .

Description

X-ray detector and X-ray imaging device using the same {X-ray detector and X-ray apparatus using the same}

The present invention relates to an X-ray detector and an X-ray imaging device using the same, and more specifically, an X-ray imaging device capable of AEC (Auto Exposure Control) or Auto Trigger of the X-ray detector itself according to an X-ray imaging mode. It is about.

A mammography apparatus, which is an example of an X-ray imaging device, is for early diagnosis of breast cancer or microcalcification, etc., radiates a certain amount of X-rays to the breast, which is a subject, and transmits the X-rays that have passed through the breast to a sensor. By receiving light, a two-dimensional X-ray image of the breast (hereinafter referred to as a two-dimensional image) or a three-dimensional X-ray image (hereinafter referred to as a three-dimensional image) is implemented.

Mammography scans include full-field digital mammography (FFDM) scans, digital breast tomosynthesis (DBT) or breast tomosynthesis (BTS) scans, and breast computed tomography (BCT) scans.

FFDM imaging is a imaging method for early diagnosis of breast cancer by obtaining two-dimensional images, DBT imaging is a imaging method in which an X-ray source is moved at a certain angle to increase the detection rate of masses that are difficult to identify in FFDM imaging, and BCT The mode is a photographing method in which an X-ray light source and a sensor are rotated over a certain angle to obtain a three-dimensional image so that the location information of the lesion can be known in detail.

An object of the present invention is to provide an X-ray detector having more improved characteristics and an X-ray imaging device using the same.

Specifically, an object of the present invention is to provide an X-ray imaging device capable of auto exposure control (AEC) or auto trigger of an X-ray detector itself according to the type of X-ray imaging.

In order to achieve the above object, the present invention is a plurality of image pixels arranged in a matrix form along row lines and column lines and accumulating electric charges for generating an X-ray image signal in a main frame section during X-ray irradiation. Including, some of the plurality of image pixels are defined as function pixels for detecting whether or not the X-ray is irradiated or detecting the amount of radiation, and the plurality of image pixels including the function pixels are during the main frame section or the main frame section. read out at a first frame rate after a frame period, and the functional pixels have a second frame rate higher than the first frame rate in a waiting period before the X-ray irradiation and a detection period before the main frame period after the start of the X-ray irradiation Provides an X-ray detector that is read out as

Here, the quantity ratio of the functional pixels to the plurality of image pixels may be 0.23% to 3.0%, and the density per unit area of the functional pixels may be 43 to 600 [number/cm 2 ].

It may further include a reset period in which the plurality of image pixels including the functional pixels are reset before the detection period and the main frame period.

The X-ray detector generates the X-ray image signal for each photographing mode, and the photographing mode is a retrofit mode and a full-field digital mammography (FFDM) mode, continuously irradiating X-rays and intermittently BTS (breast tomosynthesis or digital breast tomosynthesis) mode of continuous readout that reads out image signals, pulsed readout that intermittently irradiates X-rays and reads out the X-ray image signals At least one of a BTS mode is included, wherein the functional pixel detects whether or not the X-ray is irradiated in the retrofit mode, detects the X-ray irradiation amount in the FFMD mode, and detects the X-ray irradiation amount in the continuous readout BTS mode. It is possible to detect the irradiation amount and detect whether or not the X-rays are irradiated in the BTS mode of the pulsed readout.

The X-ray detector according to the present invention utilizes some of the image pixels as function pixels to appropriately perform AEC or auto-trigger according to the type of X-ray imaging, and uses function pixels during the main frame section for X-ray imaging. An X-ray image can be realized through all pixels in the X-ray detector, including

Therefore, AEC or auto-trigger can be performed in a relatively short time because the function is performed using only function pixels that are part of the total pixels, while more accurate AEC or auto-triggering can be performed by appropriately arranging function pixels over the entire area of the actual X-ray detector. Auto trigger can be performed.

1 is a perspective view of an X-ray imaging apparatus according to an embodiment of the present invention;
2 is a diagram schematically showing the configuration of an X-ray detector according to an embodiment of the present invention.
3 is a schematic diagram of each pixel structure of an X-ray detector according to an embodiment of the present invention;
4 is a schematic diagram of an X-ray detector according to an embodiment of the present invention.
5 is a diagram illustrating an operation sequence of an X-ray detector according to an imaging type of an X-ray imaging apparatus according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 is a perspective view of a mammography device according to an embodiment of the present invention. Hereinafter, for convenience, a mammography device will be described as an example of an X-ray imaging device according to the present invention, but the present invention is not limited thereto.

As shown, the mammography apparatus according to the embodiment of the present invention includes a main body 100 for X-ray imaging and a column 200 supporting the main body 100.

The column 200 has a vertical column shape with a lower end fixed to the floor, and the main body 100 moves up and down along the longitudinal direction of the column 200 .

The main body 100 represents a C-shape or similar shape with both upper and lower ends facing each other. The body 100 includes a column connecting portion 110 connected to the column 200 so as to be able to move up and down along the column 200, and a vertical connecting portion 120 connected to the column connecting portion 110 so as to be rotatable with respect to the column connecting portion 110. can include

One end of the main body 100, for example, the upper end, is equipped with a generator 130 to irradiate X-rays toward the other end, the lower end, and the other end, for example, the lower end of the main body 100, is equipped with an X-ray detector 140 X-rays transmitted through the inspected object placed in between are received. In addition, the body 100 may include a compression pad 150 between the generator 130 and the X-ray detector 140 to press the breast placed on the X-ray detector 140 or the support panel 160 .

At this time, in the mammography device according to the embodiment of the present invention, the entire main body 100 rotates at a certain angle to perform full-field digital mammography (FFDM) shooting, and the upper end of the main body 100 is relative to the lower end at a certain angle It can be rotated to take a digital breast tomosynthesis (DBT) or breast tomosynthesis (BTS) scan.

On the other hand, the X-ray detector 140 generates an image signal according to the positional intensity of X-rays penetrating the breast. The X-ray detector 140 for this purpose has a form in which a plurality of sensors are two-dimensionally arranged in pixel units, and a form in which unit pixel sensors form a plurality of matrices and are arranged in a matrix form.

Hereinafter, the X-ray detector 140 capable of AEC (Auto Exposure Control) or Auto Trigger of the X-ray detector itself according to the shooting mode of mammography will be described in more detail.

Prior to a detailed description, AEC (Auto Exposure Control) is a technology for controlling X-ray exposure during X-ray imaging. Accordingly, it refers to a technology that controls the tube voltage and tube current of the generator. However, as digital radiography (DR) became common, the application of the ion chamber became practically impossible, and accordingly, it was common to form a separate AEC sensor in the X-ray detector to perform the corresponding function.

However, in this embodiment, some of the image pixels in the X-ray detector for generating an X-ray image signal are used as function pixels, but the function pixels are AEC for detecting the amount of X-ray irradiation or detecting whether or not X-ray irradiation is necessary. It has an auto trigger function, and other than that, it is characterized by performing faster and more accurate AEC or auto trigger by operating with normal image pixels. Below, for convenience, a function pixel that also serves as an AEC or auto trigger function is referred to as an AEC pixel.

2 is a diagram schematically showing the configuration of an X-ray detector according to an embodiment of the present invention, and FIG. 3 is a diagram schematically showing each pixel structure of the X-ray detector according to an embodiment of the present invention.

Referring to FIGS. 2 and 3 , the X-ray detector 140 of this embodiment may include a pixel array defined in an active area of a substrate (eg, a CMOS substrate). The pixel array is composed of pixels P arranged in a matrix form along a plurality of row lines and a plurality of column lines.

Here, each pixel P functions as an image sensor for generating an X-ray image signal in a general X-ray imaging mode. In addition, some of the total pixels P of the pixel array correspond to functional pixels having both AEC and auto trigger functions, so-called AEC pixels.

Although not specifically shown, the X-ray detector 140 may include a row control circuit and a read-out circuit.

The row control circuit controls the pixel array in units of row lines. The row control circuit sequentially outputs selection signals in units of row lines, and in response thereto, a pixel P of a corresponding row line may be selected.

The read-out circuit is connected to a signal output line extending along each column line, and reads out a pixel signal output from a pixel of a row line selected through the signal output line. The read-out circuit can convert an input pixel signal into a digital signal.

The pixel P may include a photodiode PD to detect X-rays as electrical signals. In addition, a plurality of transistors may be provided in the pixel P. In this embodiment, a 3T structure pixel P having three transistors will be described as an example.

In this case, the pixel P may include a reset transistor Tr, a source follow transistor Tsf, and a selection transistor Tse.

The reset transistor Tr performs a reset function for the pixel P. The gate electrode of the reset transistor Tr receives the reset signal RS, the source electrode receives the high potential power supply voltage VDD as the first power supply voltage VDD, and the drain electrode is connected to the photodiode PD. can

The source follow transistor Tsf performs a buffer function for a pixel signal, that is, a voltage generated at the node N according to X-ray irradiation. The gate electrode of the source follow transistor Tsf is connected to the node N between the reset transistor Tr and the photodiode PD, the source electrode receives the first power supply voltage VDD, and the drain electrode is a selection transistor (Tse).

* The selection transistor Tse performs a function of outputting a pixel signal according to the selection signal SEL. A gate electrode of the selection transistor Tse may receive the selection signal SEL, a source electrode may be connected to a drain electrode of the source follow transistor Tsf, and a drain electrode may be connected to the signal output line RL.

The anode, which is the first electrode of the photodiode PD, is applied with a ground voltage as a low potential power voltage, for example, as the second power supply voltage (GND), and the cathode, which is the second electrode, is the reset transistor (Tr). may be connected to the drain electrode of

Hereinafter, an AEC pixel, which is a function pixel of an X-ray detector, will be described in more detail with reference to FIG. 4 .

FIG. 4 is a schematic diagram of an X-ray detector according to an embodiment of the present invention. For convenience of description, an AEC pixel (Pa), which is a functional pixel, is highlighted and a general image pixel (P) different from the functional pixel is not shown.

The pixel size of each pixel P may be 50um to 90um, preferably 70um, but is not limited thereto. And, the length of the active area where the pixel array is defined is (29cm2~33.5cm2)*(22cm2*23.5cm2), preferably 30.3cm2*23.1cm2, and the ratio of width and height is 1.2~ 1.52 may be preferably 1.31, but is not limited thereto.

In addition, the first frame rate at the time of generating the X-ray image signal may be 1 fps to 10 fps, preferably 2 fps to 8 fps, but is not limited thereto.

Meanwhile, the interface of the X-ray detector may support Gig E (Gigabit Ethernet) and USB.

Meanwhile, the AEC pixels (Pa) of the X-ray detector 140 according to the present embodiment may be uniformly disposed over the total area of the X-ray detector 140, that is, the entire active area.

Regarding the arrangement of the AEC pixels Pa, in this embodiment, it is assumed that the number of horizontal (rows)*vertical (columns) in which the pixels P are arranged in the active area has 110*162 to 408*590. That is, it is said that the total number of pixels P is 17820 to 240720.

At this time, the quantity ratio (ie, density) of the AEC pixels Pa to all pixels P may be 0.23% to 3%.

Also, the number (density) of AEC pixels (Pa) per unit area (cm 2 ) may be 43 [pcs/cm 2 ] to 600 [pcs/cm 2 ].

In addition, the frame rate of the AEC pixel (Pa), that is, the second frame rate of the AEC pixel (Pa) during the AEC function or the auto trigger function may be 50 fps to 500 fps, preferably 100 fps to 416 fps. And, when the AEC pixel (Pa) functions as a general image pixel (P) in the same way as the other pixels (P), it can operate at the same first frame rate as the other image pixels (P). The first frame rate is much lower than the second frame rate.

Meanwhile, in this embodiment, at this time, the AEC pixels Pa may be non-uniformly distributed with respect to the active area. That is, the intervals between neighboring AEC pixels Pa are not uniform and may vary according to positions. In this regard, reference may be made to FIG. 4, in which various numerical values such as 11, 12, 20, 21, and 22 (mm) are displayed as intervals between AEC pixels (Pa).

As such, the AEC pixels Pa may be arranged at different distances according to the positions of the AEC pixels Pa, and may be substantially non-uniformly distributed.

The AEC pixel (Pa) of this embodiment can perform various functions according to the shooting mode of mammography in addition to functions such as AEC. It is a diagram showing the operation sequence.

First, the retrofit mode is a normal X-ray detector sequence without an AEC function, and the AEC pixel performs an auto-trigger function for detecting whether or not X-rays are irradiated. That is, in the waiting period for X-ray irradiation, AEC pixels operate in an auto-trigger mode (TRG Mode) that detects whether or not X-ray irradiation occurs, and when X-ray irradiation is detected on AEC pixels, the X-ray detector resets all pixels. Through section A, X-rays are received during the main frame section to accumulate charges (integration). Then, when the X-ray irradiation is completed, a read-out period (R) in which charges charged in all pixels of the X-ray detector are read out proceeds, and then a standby mode (Stand by) is entered to wait for the next X-ray irradiation.

Next, the FFDM AEC mode is a case where the AEC function is performed in FFDM, and the AEC pixel detects the amount of X-ray irradiation at the same time as the X-ray irradiation without a separate pre-exposure, and the control unit of the mammography device detects the AEC pixel according to the detection result. The generator's tube current and/or tube voltage are appropriately determined and controlled. This AEC operation proceeds during the AEC mode period (AEC) shown in the drawing. In this AEC mode section, charges are accumulated in the AEC pixels and read out, and the control unit determines and controls the amount of X-rays according to the detection result by the AEC pixels. After resetting all pixels, the X-ray detector enters standby mode through the main frame section and the lead-out section (R), similar to retrofit.

Next, the BTS AEC mode is a mode in which the BTS performs an AEC function, and the continuous readout among the BTS AEC modes is a case in which the BTS performs continuous X-ray irradiation. In this case, the AEC pixels sense X-rays simultaneously with X-ray irradiation without separate prior exposure, and the control unit of the mammography device appropriately determines and controls the tube current and/or tube voltage of the generator through the detection results of the AEC pixels. This AEC operation proceeds during the AEC mode period (AEC) shown in the drawing. Thereafter, the X-ray detector resets all pixels, periodically performs a read-out period (R) for reading out charges charged in all pixels multiple times, and enters a standby mode when X-ray irradiation is completed.

Next, in the BTS AEC mode, Pulsed Readout is a case where BTS is performed through intermittent X-ray irradiation, and in the waiting period for X-ray irradiation, the AEC pixel detects whether or not the X-ray is irradiated. mode, and when X-ray irradiation is detected on AEC pixels, the X-ray detector receives X-rays during the main frame period (MF) for the first pulse X-rays through a reset period (A) in which all pixels are reset, A read-out period (R) in which charges charged in all pixels of the X-ray detector are read out is performed. Subsequently, the auto trigger section (T), reset section (A), main frame section (MF), and readout section (R) are repeated in unit cycles according to the X-ray irradiation pulse, and when all X-ray irradiation is completed, the standby mode ( Stand by).

Meanwhile, in the aforementioned retrofit mode or the pulsed readout mode of the BTS AEC, the AEC mode section can be set. That is, immediately after the auto trigger mode period, the AEC mode period may be performed, and then the reset period (A) may be performed.

As described above, the X-ray detector according to the present embodiment utilizes some of the image pixels as function pixels to appropriately perform AEC and auto-trigger according to the type of shooting of the mammography device, and to perform X-ray image shooting. During the main frame section for the first time, an X-ray image can be realized through all pixels in the X-ray detector including functional pixels.

Therefore, AEC and auto-trigger can be performed in a relatively short time because the function is performed using only function pixels, which are a part of all pixels, while function pixels are appropriately placed over the entire area of the actual X-ray detector to achieve more accurate AEC and Auto trigger can be performed.

Meanwhile, an embodiment of the present invention may be applied not only to a mammography device but also to an X-ray imaging device for other purposes.

The above-described embodiment of the present invention is an example of the present invention, and free modification is possible within the scope included in the spirit of the present invention. Accordingly, this invention covers the modifications and variations of this invention within the scope of the appended claims and their equivalents.

100: body 110: column connection
120: vertical connection part 130: generator
140: X-ray detector 150: compression pad
160: support panel 200: column
P: pixel
Pa: AEC pixels
PD: Photodiode
Tr: reset transistor
Tsf: source follow transistor
Tse: selection transistor

Claims (4)

comprising a plurality of image pixels arranged in a matrix form along row and column lines;
As an X-ray detector that operates while passing through the waiting period before X-ray irradiation, the detection period during X-ray irradiation, the reset period, the main frame period, and the read-out period in order,
Some of the plurality of image pixels are read out at a first frame rate in the waiting period and the sensing period to detect whether or not X-rays are irradiated or to detect the amount of radiation;
All of the plurality of image pixels are reset in the reset section and read out at a second frame rate in the main frame section or readout section to implement an X-ray image;
The first frame rate is higher than the second frame rate X-ray detector. According to claim 1,
The quantity ratio of some pixels that are read out at the first frame rate in the waiting section and the detection section for the plurality of image pixels to detect whether X-rays are irradiated or to detect the amount of irradiation is 0.23% to 3.0%,
The density per unit area of some pixels that are read out at the first frame rate in the waiting section and the detection section to detect whether X-rays are irradiated or to detect the amount of irradiation is 43 to 600 [number/cm 2 ] X-ray detector. delete According to claim 1,
The X-ray detector generates an X-ray image signal for each shooting mode,
The photographing mode includes a retrofit mode, a full-field digital mammography (FFDM) mode, continuous readout of continuous readout (BTS) that continuously irradiates X-rays and intermittently reads out the X-ray image signal at least one of a tomosynthesis or digital breast tomosynthesis mode and a pulsed readout BTS mode for intermittently irradiating X-rays and reading out the X-ray image signal,
Some pixels that are read out at the first frame rate in the waiting period and detection period and detect whether or not X-rays are irradiated or detect the irradiation amount detect whether or not the X-rays are irradiated in the retrofit mode, and in the FFDM mode, the X-rays An X-ray detector that detects an irradiation amount, detects the X-ray irradiation amount in the continuous readout BTS mode, and detects whether or not the X-ray irradiation occurs in the pulsed readout BTS mode.

Images