JP2009279295A - Radiographic imaging apparatus and image processing device - Google Patents

Abstract

An image with a desired magnification is obtained without information on geometric positional relationships.
Image acquisition means for acquiring a radiographic image obtained by imaging a correction magnification calculation marker formed of a substance having a large radiation attenuation coefficient together with a subject, and the marker imaged on the acquired radiographic image. A marker detection unit that detects an image; a marker detection result of the marker detection unit; a correction magnification calculation unit that calculates a correction magnification based on information about the marker that is set in advance; and The problem is solved by providing an image processing apparatus comprising scale correction means for correcting a scale based on the calculated correction magnification.
[Selection] Figure 2

Description

  The present invention relates to a radiographic imaging apparatus and an image processing apparatus, and in particular, irradiates a subject with radiation such as X-rays, detects the transmitted radiation, acquires a radiographic image, performs image processing, and provides for diagnosis. The present invention relates to a radiographic image capturing apparatus and an image processing apparatus.

  2. Description of the Related Art Conventionally, radiographic imaging apparatuses that irradiate a subject with radiation such as X-rays, detect the transmitted radiation, acquire a radiographic image, and use it for diagnosis are widely known. In this radiographic imaging apparatus, a radiation detector that detects radiation transmitted through a subject is known using a radiation film or a storage phosphor sheet that accumulates radiation energy.

  For example, FIG. 5 shows how a radiographic image is taken. FIG. 5A shows an imaging state in the standing position, in which the subject S standing from the radiation source 90 is irradiated with radiation, and the radiation transmitted through the subject S is irradiated. Detection is performed by a radiation detector 92 arranged on the rear side of the specimen S. Further, FIG. 5B shows an imaging state in the supine position, in which the subject S sleeping on the bed 96 is irradiated with radiation from the radiation source 90, and the subject S is exposed. The transmitted radiation is detected by a radiation detector 92 disposed below the bed 96.

  As shown in FIG. 5, the subject detected by the radiation detector 92 since the radiation is emitted radially from the radiation source 90 toward the subject S in both the standing-up imaging and the standing-up imaging. The size of the image of S is different from the actual size of the subject S. For this reason, there is a problem that the size of the region of interest is different from the actual size when performing diagnosis by displaying this image on a display means or the like.

  There are various types of radiographic imaging devices of different manufacturers and models, and the distance from the outer surface of the device to the sensor surface varies depending on the manufacturer and model, so even if the subject is placed at the same position from the outer surface of the device There is a problem that the size of the subject on the image obtained varies depending on the manufacturer and model. When a facility with multiple devices of different manufacturers or models, or when a device is replaced, the size of the subject changes even if the image is taken under the same conditions as before, making it very useful to compare these images and make a diagnosis. Inconvenient.

  Therefore, for such a problem, it is considered to output an image in actual size so that the size of the attention site can be easily grasped intuitively.

For example, a first distance from the focal point of the X-ray generation unit to the X-ray incident surface of the X-ray light conversion unit so that an image captured by the imaging unit is output from the output device at the same magnification as the subject; An enlargement ratio is calculated from the second distance from the focal point of the X-ray generation means to the center of the subject, the image output size, and the size of the X-ray incident surface, and the image from the imaging means is enlarged based on the calculated enlargement ratio An X-ray diagnostic apparatus is known that outputs an image in actual size by outputting the image (for example, see Patent Document 1).
JP-A-7-265286

  However, the one described in the above patent document measures the geometric positional relationship (distance information) and corrects the magnification of the image, but is configured by combining radiation sources and radiation detectors from different manufacturers. In the case of a system or the like, information on the geometric positional relationship is not always available.

  The present invention has been made in view of such circumstances, and provides a radiographic image capturing apparatus and an image processing apparatus that can obtain an image with a desired magnification without information on a geometric positional relationship. Objective.

  In order to achieve the above object, the invention according to claim 1 is an image acquisition means for acquiring a radiographic image obtained by photographing a correction magnification calculation marker formed of a substance having a large radiation attenuation coefficient together with a subject. Correction for calculating a correction magnification based on marker detection means for detecting an image of the marker captured in the acquired radiographic image, marker detection result of the marker detection means, and information on the marker set in advance An image processing apparatus comprising: a magnification calculation unit; and a scale correction unit that corrects the scale of the subject in the radiation image based on the calculated correction magnification.

  As a result, an image with a desired magnification can be obtained without the information on the geometric positional relationship.

  Further, according to a second aspect of the present invention, the image processing apparatus further includes a scale acquisition unit that acquires a desired scale with respect to the scale of the subject in the radiographic image, and the correction magnification calculation unit applies the acquired scale to the desired scale. Based on this, the correction magnification is calculated.

  Thus, an image with a desired magnification can be obtained by the operator inputting the scale.

  In addition, according to a third aspect of the present invention, the marker detecting unit detects the size of the marker on the radiographic image, and the correction magnification calculating unit is preset with the size of the detected marker. The correction magnification is calculated based on the actual size of the marker.

  As a result, an image having the same magnification as the actual size can be obtained only by detecting the size of the marker without detecting the position of the marker on the image.

  In addition, according to a fourth aspect of the present invention, the image acquisition unit acquires a radiographic image obtained by capturing a plurality of the correction magnification calculation markers together with the subject, and the marker detection unit includes a plurality of the markers. The position on the radiographic image is detected, and the correction magnification calculation means calculates the correction magnification based on the detected positions of the plurality of markers and the actual positions of the plurality of markers set in advance. It is characterized by.

  Thereby, it is possible to obtain an image having the same magnification as the actual size without detecting the size of the marker only by detecting the positions of the plurality of markers on the image.

  Similarly, in order to achieve the object, the invention according to claim 5 includes a radiation source that emits radiation, a radiation detector that detects radiation emitted from the radiation source and transmitted through the subject, and A correction magnification calculation marker formed of a substance having a large radiation attenuation coefficient, which is arranged at a position where the image is detected by the radiation detector together with the subject, and detected by the radiation detector A radiographic imaging apparatus comprising: the image processing apparatus according to any one of claims 1 to 4 that performs image processing on a radiographic image obtained by imaging the subject and the marker together. provide.

  As a result, an image with a desired magnification can be taken without any information on the geometric positional relationship.

  In addition, as described in claim 6, when the radiographic image capturing apparatus further moves the radiological detector so as to partially overlap each other and captures a plurality of images, the posture of the subject is maintained. In order to achieve this, the partition formed between the subject and the radiation detector is formed of a radiation transmissive material, and the partition surface is used as a mark when the plurality of images are combined. And a long alignment marker formed of a material having a large radiation attenuation coefficient, and a radiographic imaging device that obtains an image of a subject longer than the maximum field of view of the radiation detector. The long alignment marker is also used as the correction magnification calculation marker.

  Thereby, a long radiation image can be taken at the same magnification as the actual size.

  As described above, according to the present invention, it is possible to capture an image with a desired magnification without the information on the geometric positional relationship.

  Hereinafter, a radiographic imaging apparatus and an image processing apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing an embodiment of a radiographic imaging apparatus according to the present invention.

  As shown in FIG. 1, the radiographic image capturing apparatus 10 of the present embodiment is an X-ray image capturing apparatus that captures an X-ray image of a subject using X-rays as radiation, and is mainly applied to the subject S. From an X-ray source 12 that irradiates X-rays, a flat panel X-ray detector (FPD) 14 that detects X-rays transmitted through the subject S and outputs a detection signal, an X-ray controller 16 and a console 18 Composed.

  The console 18 is connected to a display 20 for displaying a photographed X-ray image. The screen of the display 20 is also a touch panel on which an operator can touch to input a predetermined instruction or the like. . Further, the console 18 may be connected to other input means such as a keyboard.

  Although the detailed description of the X-ray source 12 is omitted, the X-ray source 12 has an X-ray tube that irradiates the subject S with X-rays, and the energy of the X-rays emitted by a predetermined tube voltage and tube current is controlled. It has become so.

  The light receiving surface of the FPD 14 is formed in a flat plate shape, and the inclination of the FPD 14 can be changed so that the light receiving surface is vertical or horizontal according to, for example, imaging in a standing position and a supine position. The transmitted X-rays are detected photoelectrically and an analog electric signal is output.

  An output signal (detection signal) of the FPD 14 is input to the console 18 via the X-ray controller 16.

  The X-ray controller 16 controls the X-ray source 12 and the FPD 14 to perform X-ray imaging. That is, the X-ray image is controlled by controlling the tube voltage of the X-ray source 12 to a predetermined value based on the input imaging conditions or the set imaging conditions.

  In the present embodiment, a marker whose size and positional relationship are known in advance is photographed together with the subject S, the marker is detected from the obtained image, the size of the marker detected from the image and the actual marker The magnification correction is performed on the image of the subject S based on the size.

  Therefore, at the time of imaging, imaging is performed by placing a marker having a predetermined shape and a predetermined size formed of a substance having a large radiation attenuation coefficient on the surface of the apparatus on which the FPD 14 is installed or on the subject S. At the same time, the marker is taken in the X-ray image together. In addition, in the case of long imaging, a marker is arranged on a partition surface for maintaining the posture of the subject S in the standing position, or on the bed surface on which the subject S lies in the lying position. It may be arranged.

  In any case, it is preferable that the positional relationship between the subject S and the marker is always a predetermined relationship. For example, if the marker is arranged on the apparatus surface and the subject S is always photographed at a predetermined position from the apparatus surface, the positional relationship between the subject S and the marker can be kept substantially constant.

  The console 18 receives a detection signal of the FPD 14 representing an X-ray image captured via the X-ray controller 16, reconstructs a fluoroscopic image to be imaged, generates a predetermined image, and displays it on the display 20. At that time, an image processing device in the console 18 described later detects a marker imaged together with the subject S from the X-ray image, calculates a correction magnification based on the detection result, and then subjects the subject S. Try to correct the image scale.

  The display 20 displays a photographed X-ray image, inputs an order such as a photographing menu and a photographing part by a touch panel operation, inputs a photographing condition of a first image as a normal diagnostic image, and photographs in advance. It is also used to input an adjustment value when conditions are set as initial values.

  The radiographic image capturing apparatus 10 in the present embodiment uses X-rays as radiation, captures an X-ray image of a subject together with a marker having a predetermined size, and detects the size of the marker in the captured X-ray image. By correcting the image so that the size of the detected marker is a predetermined size (magnification correction), the captured image of the subject is output at a desired magnification. This is performed in an image processing apparatus included in the console 18.

  FIG. 2 shows a configuration of the image processing apparatus included in the console 18 in the present embodiment.

  As shown in FIG. 2, the image processing apparatus included in the console 18 mainly includes an image acquisition unit 22, a marker detection unit 24, a correction magnification calculation unit 26, and a scale correction unit 28. Further, the correction magnification calculation means 26 is provided with a marker information database 30 that stores the actual size of the marker, and a scale acquisition means 32 that receives a desired scale.

  The image acquisition means 22 receives the detection signal irradiated from the X-ray source 12 to the subject S, transmitted through the subject S and detected by the FPD 14 from the X-ray controller 16 as an X-ray image.

  The marker detection unit 24 receives an X-ray image from the image acquisition unit 22 and detects a marker from the image. At this time, the size of the marker is particularly detected. It is not always necessary to detect the position of the marker. The marker detection method is not particularly limited, and any known pattern recognition technique can be used.

  For example, a marker pattern may be stored in advance in the storage unit (marker information database 30), and template matching may be performed on the Gaussian pyramid to specify the marker position and the marker size. At this time, for example, if the shape of the marker is a simple shape such as a circle, the size of the marker can be detected by combining a calculation such as a filter operation or a morphology operation and a threshold value processing without storing the pattern itself. can do.

  The correction magnification calculating unit 26 calculates a correction magnification for making the photographed marker an actual size from the size of the marker detected by the marker detection unit 24 and the actual size of the marker held in the marker information database 30. Is to be calculated.

  For example, when the marker is a circular marker having a diameter m = 1 [cm], the marker diameter on the detected image is a = 55 [pixel] (the pixel interval is now d = 200 [μm]). )), The correction magnification s can be calculated as follows.

s = m ÷ (a × d) = 1 × 10 ⁻² ÷ (55 × 200 × 10 ⁻⁶ ) = 1 / 1.1
As shown in FIG. 2, a scale acquisition unit 32 is provided, and a correction scale for inputting a desired scale from the outside or acquiring from a system setting or the like and correcting to the desired scale using the acquired scale is provided. You may make it ask.

  For example, when the desired scale is x, the correction magnification s is calculated by the following equation.

s = (m × x) ÷ (a × d)
The scale correction unit 28 performs magnification correction on the X-ray image of the subject S based on the correction magnification calculated by the correction magnification calculation unit 26 and performs enlargement processing or reduction processing so as to obtain a desired magnification. is there.

  Next, as a function of the radiographic image capturing apparatus and the image processing apparatus of the present invention having the above-described configuration, a first embodiment of the present invention using one marker will be described.

  First, as shown in FIG. 3A, one X of a predetermined marker 36 is arranged on the surface of the FPD 14 when an X-ray image is taken. At this time, it arrange | positions in the position where the marker 36 is reflected in the sensor surface 34 of FPD14.

  An X-ray image is taken by irradiating the subject S with X-rays from the X-ray source 12 and projecting the marker 36 together with the subject S onto the sensor surface 34.

  The photographed X-ray image is taken into the image processing device of the console 18 by the image acquisition means 22. FIG. 3B shows an X-ray image 40 taken. However, the display of the image of the subject S is omitted. As shown in FIG. 3B, an image 42 of the marker 36 is shown at the end of the X-ray image 40. The captured X-ray image 40 is transferred to the marker detection means 24.

  Next, the marker detection unit 24 detects the size of the marker image 42 from the X-ray image 40. As described above, the detection method is not particularly limited, and a known pattern recognition technique can be used. At this time, it is not necessary to detect the position of the marker image 42 in the X-ray image 40. For example, if the marker 36 is circular, the value of its diameter is detected.

  Next, the correction magnification calculation means 26 uses the detected size of the marker image 42 and the actual size of the marker 36 held in the marker information database 30 to obtain a correction magnification for making the marker image 42 an actual size. calculate.

  For example, when the marker 36 is circular and its diameter is d, the diameter of the marker image 42 is a, and the pixel interval of the X-ray image 40 is d, the correction magnification s can be calculated by the following equation.

s = m ÷ (a × d)
Alternatively, a scale may be input from the scale acquisition means 32, and a correction magnification may be obtained by the following formula to correct it to a desired scale x.

s = (m × x) ÷ (a × d)
Next, the scale correction means 28 corrects the magnification of the image of the subject S with the correction magnification s calculated above.

  The magnification-corrected X-ray image 40 is displayed on the display 20 and is output to other image output means or an image recording medium.

  As described above, in the present embodiment, one marker is arranged and photographed together with the subject S, the size of the photographed marker is detected, the correction magnification is obtained, and the magnification of the image of the subject S is corrected. Thus, a subject image with a desired magnification can be obtained without measurement information regarding the geometric positional relationship of the imaging system such as the distance between the X-ray source and the sensor surface.

  Next, a second embodiment of the present invention will be described.

  The second embodiment uses a plurality of markers. For example, as shown in FIG. 4A, two predetermined markers 36 are arranged on the surface of the FPD 14 in capturing an X-ray image. At this time, the marker 36 is arranged at a position where the marker 36 does not interfere with the imaging of the region of interest of the subject S and the marker 36 appears on the sensor surface 34 of the FPD 14.

  The photographed X-ray image is taken into the image processing device of the console 18 by the image acquisition means 22. FIG. 4B shows an X-ray image 40 taken. However, the display of the image of the subject S is omitted. As shown in FIG. 4B, the images 42 of the two markers 36 are shown at the end of the X-ray image 40. The captured X-ray image 40 is transferred to the marker detection means 24.

  Next, the marker detection unit 24 detects the positions of the plurality of marker images 42 in the X-ray image 40 from the X-ray image 40. At this time, the size of the marker image 42 is not necessarily detected. The method for detecting this position is the same as in the first embodiment described above, and a known pattern recognition technique may be used.

  Next, the correction magnification calculation means 26 obtains the interval from the detected positions of the two marker images 42 and uses this and the actual arrangement interval of the two markers 36 held in the marker information database 30. A correction magnification for making the marker image 42 an actual size is calculated.

  For example, when two markers 36 are arranged on the surface of the FPD 14 with an interval m = 30 [cm], the interval between the marker images 42 on the X-ray image 40 is a = 1650 [pixel] (pixel interval d = 200 [μm]), the correction magnification s is as follows.

s = m ÷ (a × d) = 30 × 10 ⁻² ÷ (1650 × 200 × 10 ⁻⁶ ) = 1 / 1.1
Similarly to the first embodiment described above, a scale may be input from the scale acquisition unit 32, a correction magnification may be obtained by the following equation, and corrected to a desired scale x.

s = (m × x) ÷ (a × d)
Next, the scale correction means 28 corrects the magnification of the image of the subject S with the correction magnification s calculated above.

  The magnification-corrected X-ray image 40 is displayed on the display 20 and is output to other image output means or an image recording medium.

  As described above, in the present embodiment, two markers are arranged and photographed together with the subject S, the positions of the two photographed markers are detected, and the correction magnification is obtained from the interval between the two marker images. Thus, the magnification of the image of the subject S is corrected. As a result, a subject image with a desired magnification can be obtained without measurement information regarding the geometric positional relationship of the imaging system such as the distance between the X-ray source and the sensor surface, as in the first embodiment. .

  In the embodiment described above, in order to calculate the correction magnification, the marker is particularly arranged and the image is taken together with the subject. However, the marker is not particularly arranged in this way, and another one is substituted. You may do it.

  For example, in long shooting, a long image is obtained by moving an FPD so that a portion of each portion overlaps, shooting a plurality of images, and combining the overlapping portions. A long alignment marker used for combining multiple images with overlapping portions may be used also as a marker for calculating the correction magnification in this embodiment.

  Further, in the case of long imaging, the FPD is moved and imaging is performed a plurality of times, so that it takes time to perform imaging. Therefore, the screen is arranged so that the subject S keeps the posture as much as possible. It is preferable to place a marker on the top.

  The marker for calculating the correction magnification may be embedded in the apparatus or the like, or may be detachable and installed every time shooting is performed.

  The radiographic imaging apparatus and the image processing apparatus of the present invention have been described in detail above, but the present invention is not limited to the above examples, and various improvements and modifications are made without departing from the gist of the present invention. Of course.

It is a schematic block diagram which shows one Embodiment of the radiographic imaging apparatus which concerns on this invention. It is a schematic block diagram which shows the image processing apparatus contained in the console in this embodiment. (A) is explanatory drawing which shows the mode of the X-ray image imaging | photography in 1st Embodiment of this invention, (b) is explanatory drawing which shows the image | photographed X-ray image. (A) is explanatory drawing which shows the mode of the X-ray image imaging | photography in 2nd Embodiment of this invention, (b) is explanatory drawing which shows the image | photographed X-ray image. It is explanatory drawing which shows the mode of the conventional radiographic image imaging | photography, (a) is a case of standing position imaging | photography, (b) is a case of supine position imaging | photography.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Radiation imaging device, 12 ... X-ray source, 14 ... FPD, 16 ... X-ray controller, 18 ... Console, 20 ... Display, 22 ... Image acquisition means, 24 ... Marker detection means, 26 ... Correction magnification calculation means, 28 ... Scale correction means, 30 ... Marker information database, 32 ... Scale acquisition means, 34 ... Sensor surface, 36 ... Marker, 40 ... X-ray image, 42 ... Marker image

Claims (6)

An image acquisition means for acquiring a radiographic image obtained by imaging a marker for correction magnification calculation formed of a substance having a large radiation attenuation coefficient together with the subject;
Marker detection means for detecting an image of the marker imaged in the acquired radiographic image;
Correction magnification calculation means for calculating a correction magnification based on a marker detection result of the marker detection means and information on the marker set in advance;
Scale correction means for correcting the scale of the subject in the radiation image based on the calculated correction magnification;
An image processing apparatus comprising:   Scale acquisition means for acquiring a desired scale with respect to the scale of the subject in the radiation image, and the correction magnification calculation means calculates the correction magnification based on the acquired desired scale. The image processing apparatus according to claim 1, wherein:   The marker detecting means detects the size of the marker on the radiographic image, and the correction magnification calculating means is based on the size of the detected marker and a preset actual size of the marker. The image processing apparatus according to claim 1, wherein the correction magnification is calculated.   The image acquisition means acquires a radiographic image obtained by photographing a plurality of correction magnification calculation markers together with the subject, and the marker detection means detects positions of the plurality of markers on the radiographic image. The correction magnification calculation means calculates the correction magnification based on the detected positions of the plurality of markers and the actual positions of the plurality of markers set in advance. The image processing apparatus described. A radiation source that emits radiation;
A radiation detector that detects radiation emitted from the radiation source and transmitted through the subject;
A marker for calculating a correction magnification, which is formed of a substance having a large radiation attenuation coefficient, which is arranged at a position such that the image is detected by the radiation detector together with the subject;
The image processing apparatus according to any one of claims 1 to 4, wherein image processing is performed on a radiographic image taken together with the subject and the marker detected by the radiation detector;
A radiographic imaging apparatus comprising:   When the radiographic image capturing apparatus further captures a plurality of images by moving the radiation detector so that portions of the radiographic image capturing apparatus overlap each other, the subject and the radiation are maintained. A substance having a large radiation attenuation coefficient arranged between the detectors and arranged along the screen so as to serve as a mark when combining the screens formed of a radiation transmissive material and the plurality of images. And a long alignment marker formed by the radiological image capturing apparatus for obtaining an image of a subject longer than the maximum field of view of the radiation detector. 6. The radiographic image capturing apparatus according to claim 5, wherein the radiographic image capturing apparatus is also used as a marker for calculating a correction magnification.

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