JP2006187501A - Radiographic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiographic system capable of surely forming a precise boundary position when failing to automatically detect a boundary position of a transmission image region. <P>SOLUTION: When an automatic boundary detecting means 70 fails to automatically detect the boundary of the chest wall position when picking a display image region from an output image region, a boundary calculation means 71 automatically detects a marker boundary position never failing to automatically detect the boundary, calculates the chest wall position from the marker boundary position based on marker disposed position information on an imaging table to pick the display image region. Even if the automatic boundary detecting means 70 fails the automatic detection of the chest wall position, this constitution can surely find the proper chest wall position and make the display image easy to see for an operator. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an X-ray imaging apparatus for acquiring transmission image information of a subject placed on an imaging table, and a display image consisting only of transmission image information from output image information of the X-ray imaging apparatus including the transmission image information. The present invention relates to an X-ray imaging system including an image processing apparatus that extracts and displays a region.

  The transmission image information of the subject acquired by an X-ray imaging apparatus such as mammography is displayed or output on an image display apparatus such as an LCD or an image output apparatus such as an imager, and is diagnosed by an operator. Here, the output image information output from the X-ray imaging apparatus includes image information of a larger area including the transmission image area where the transmission image information exists. When this image information is displayed or output, only the display image area portion of the transparent image area is extracted from the output image information and displayed or output so that the interpretation by the operator is easy to see. , See Patent Document 1).

Here, when the display image information is extracted from the output image information of the X-ray imaging apparatus, the boundary position of the transmission image region is detected. This detection is automatically performed in order to improve the operator's work efficiency. On the other hand, the detection of the boundary position is required to be particularly highly accurate when an image of the subject exists at the boundary position. For example, in mammography, where the breast part is taken as the part to be imaged, the breast wall image of the breast is always located at the boundary of the transparent image area, and accurately depicting this boundary part is a disease located at the boundary. It is indispensable to make sure that the part is correct or easy to read.
Japanese Patent Laid-Open No. 2001-222084, (first page, FIG. 1) JP 2004-261306 A, (page 3, FIG. 1)

  However, according to the above background art, when the boundary position is automatically detected, there is a case where proper detection is not performed. That is, the automatic detection of the boundary position is performed based on a change in the signal intensity of the image information. However, when the subject image exists at the boundary position, the boundary with the portion other than the peripheral subject image is not clear. An appropriate boundary position may not be detected.

  In particular, in breast imaging using mammography, the chest wall side of the breast is always the boundary position of the transparent image region, and the boundary with the part other than the transparent image information is not clear because the breast is thick or there are many mammary glands. Often happens. This unclear boundary becomes a factor in detecting an incorrect boundary position.

For these reasons, it is important how to realize an X-ray imaging system that can reliably set an appropriate boundary position when the boundary position of a transmission image area is automatically detected by mistake.
The present invention has been made in order to solve the above-described problems caused by the background art. When the boundary position of the transmission image area is erroneously automatically detected, the X-ray imaging can surely set the boundary position appropriately. The purpose is to provide a system.

  In order to solve the above-described problems and achieve the object, an X-ray imaging system according to the first aspect of the present invention includes an X-ray image detector that detects X-rays transmitted through the imaging table, on the imaging table. A display image region consisting only of the transmission image information is extracted from output image information of the X-ray imaging apparatus that acquires transmission image information of the subject placed on the X-ray imaging apparatus and the transmission image information. An X-ray imaging system comprising: an image processing device to display, wherein the X-ray imaging device has a marker for preventing transmission of the X-ray on the imaging table, and the image processing device Automatic boundary detection means for automatically detecting the boundary position of the transmission image information included in the output image information for the transmission, and the transmission image information when the automatic boundary detection means fails to detect the boundary position. Included in Based on the marker position information over Ca, and having a boundary calculating unit for calculating the boundary position.

  According to the first aspect of the present invention, the X-ray imaging apparatus has a marker for preventing X-ray transmission on the imaging table, and the image processing apparatus uses the automatic boundary detection means to output image information for extraction. The boundary position of the transmission image information included in the image is automatically detected, and when the automatic boundary detection unit fails to detect the boundary position, the boundary calculation unit uses the marker position information of the marker included in the transmission image information. To calculate the boundary position.

  According to a second aspect of the present invention, in the X-ray imaging system according to the first aspect of the present invention, the boundary calculating unit obtains the marker position information using the automatic boundary detecting unit.

According to a third aspect of the present invention, in the X-ray imaging system according to the first or second aspect, the subject of the X-ray imaging apparatus is a breast.
An X-ray imaging system according to a fourth aspect of the present invention is the X-ray imaging system according to the third aspect, wherein the X-ray imaging apparatus includes phase contrast imaging means for performing phase contrast imaging.

  According to a fifth aspect of the present invention, in the X-ray imaging system according to the third aspect of the present invention, the boundary position is a chest wall position located on a chest side of a breast image included in the transmission image information. Features.

According to a sixth aspect of the present invention, in the X-ray imaging system according to the fifth aspect of the present invention, the marker is disposed at a position facing the chest wall position on the imaging table.
An X-ray imaging system according to a seventh aspect of the invention is characterized in that, in any one of the first to sixth aspects, the marker is a stainless steel plate.

  An X-ray imaging system according to an eighth aspect of the present invention is the X-ray imaging system according to any one of the first to seventh aspects, wherein the image processing apparatus inputs arrangement position information of the marker on the imaging table. An input unit is provided.

  An X-ray imaging system according to a ninth aspect of the present invention is the X-ray imaging system according to any one of the first to eighth aspects, wherein the image processing apparatus stores the boundary position information and the stored Boundary determination means for determining the failure is provided based on statistical quantities calculated using history information consisting of boundary position information.

In the invention according to claim 9, the boundary determination means performs determination based on statistical quantities of the history information.
An X-ray imaging system according to a tenth aspect of the present invention is the X-ray imaging system according to any one of the first to ninth aspects, wherein the X-ray imaging system is used as the X-ray image detector of the X-ray imaging apparatus. An image reading device is provided for reading the imaging plate when using a detachable cassette incorporating an imaging plate.

In the invention described in claim 10, the imaging plate in the cassette is read by the image reading device.
According to an eleventh aspect of the present invention, in the X-ray imaging system according to the tenth aspect, the output image information is read image information read by the image reading device.

  An X-ray imaging system according to a twelfth aspect of the present invention is the X-ray imaging system according to the tenth or eleventh aspect, wherein the image processing apparatus includes a detachment direction determination unit that determines a detachment direction of the cassette based on the marker position information. It is characterized by.

  As described above, according to the invention described in claim 1, the X-ray imaging apparatus has a marker for preventing transmission of X-rays on the imaging table, and the image processing apparatus uses the automatic boundary detection means, The boundary position of the transmission image information included in the output image information for extraction is automatically detected, and when the automatic boundary detection unit fails to detect the boundary position, it is included in the transmission image information by the boundary calculation unit. Since the boundary position is calculated based on the marker position information of the marker, the boundary position is reliably detected regardless of the boundary position of the transmission image information, and it is easy for the operator to see, It is possible to extract a display image that can be diagnosed without any diagnosis.

  According to the second aspect of the present invention, since the boundary calculating means obtains the marker position information using the automatic boundary detecting means used for detecting the boundary position, it can have a simple configuration.

According to the third aspect of the present invention, since the subject of the X-ray imaging apparatus is the breast, a transmission image of the breast can be acquired.
According to the invention described in claim 4, since the X-ray imaging apparatus performs phase contrast imaging by the phase contrast imaging means, the boundary position can be reliably detected and a good display image can be obtained. it can.

  According to the fifth aspect of the present invention, since the boundary position is the chest wall position located on the chest side of the breast image included in the transmission image information, the depiction of the chest wall position includes only the transmission image information. It can be easy for the operator to see.

  According to the sixth aspect of the present invention, since the marker is disposed at a position opposite to the chest wall position on the imaging table, the marker image is prevented from overlapping with a breast image important for diagnosis. Can do.

According to the seventh aspect of the present invention, since the marker is a stainless steel plate, the transmission of X-rays can be reliably prevented.
According to the eighth aspect of the present invention, the input unit inputs the marker arrangement position information, so that the marker arrangement position can be changed.

According to the invention described in claim 9, since the boundary determination means performs determination based on statistical quantities of history information, it can perform appropriate determination with high probability.
According to the invention described in claim 10, since the image reading device reads the imaging plate in the cassette, the boundary position of the transmission image information even when the imaging plate is not a built-in type X-ray imaging device. Can be reliably detected.

  According to the eleventh aspect of the invention, since the output image information is read image information read by the image reading device, the boundary position of the transmission image information included in the read image information is reliably detected. be able to.

  According to the twelfth aspect of the present invention, since the image processing apparatus uses the marker position information to determine the demounting direction of the cassette by the demounting direction determination unit, the wrong direction of the cassette is also determined. The operator can recognize and display an appropriate display image.

The best mode for carrying out an X-ray imaging system according to the present invention will be described below with reference to the accompanying drawings. Note that the present invention is not limited thereby.
First, the overall configuration of the X-ray imaging system according to the present embodiment will be described with reference to FIG. FIG. 2 is a diagram showing the overall configuration of the X-ray imaging system. The X-ray imaging system includes an X-ray imaging apparatus 1, an image reading apparatus 40, an image processing apparatus 50, and a communication cable 60 that connects the image reading apparatus 40 and the image processing apparatus 50.

  The X-ray imaging apparatus 1 is an X-ray imaging apparatus for breasts. The imaging unit 3 obtains transmission image information by projecting a subject 2 (subject's breast) by X-rays, and a support base 20 that supports the imaging unit 3. And a controller 30 for operating and controlling the photographing unit 3 and the support base 20.

  The imaging unit 3 is provided with an X-ray source 4 for irradiating X-rays downward at the upper part, and the lower part of the X-ray source 4 is for restricting X-ray irradiation to unnecessary areas. An irradiation field stop 5 made of a material such as lead is disposed. In addition, an imaging table 6 that supports the subject 2 from below is disposed in the approximate center of the imaging unit 3. Above the imaging table 6, a compression plate 7 for compressing the subject 2 from above to below is disposed so as to be movable up and down.

  The imaging table 6 has a rectangular frame made of a material such as stainless steel so that it can withstand the placement of the subject 2 and the compression by the compression plate 7, and the subject 2 can be placed on the upper surface thereof. In order to prevent the X-rays that pass through the glass from being disturbed, a plate made of a material such as carbon that easily transmits X-rays is covered so as to be covered.

  In the imaging unit 3 having such a configuration, the subject performs imaging while the subject 2 is placed on the imaging table 6, and the compression plate 7 is lowered and the subject 2 is compressed and fixed on the imaging table 6. . In this state, the subject 2 supported by the imaging table 6 faces the X-ray source 4 and is located in the X-ray irradiation field irradiated from the X-ray source 4.

  A marker 16 is disposed on the imaging table 6 at a position facing the subject 2. FIG. 3 illustrates the marker 16 on the imaging table 6. The marker 16 is a plate having a rectangular shape made of a material that prevents transmission of X-rays such as stainless steel. The marker 16 has an edge on the subject 2 side located in the X-ray irradiation field of the imaging table 6 and is disposed at a predetermined position that does not interfere with imaging of the subject 2 to be placed. . The marker 16 can also be arranged on the back side of the upper surface of the imaging table 6 on which the subject 2 is placed.

  A support base 10 is disposed in a horizontal state at the lower end of the support member 8, and the support base 10 includes a detachable cassette 14 in which a fixing member 12 and an imaging plate 15 are built. These constitute phase contrast imaging means for performing phase contrast imaging. Here, an interval between the X-ray source 4 and the subject 2 and an X-ray transmission image built in the subject 2 and the cassette 14 are detected. When the distance from the imaging plate 15 is an appropriate distance, an edge effect due to phase contrast can be obtained. In order to obtain a clear phase contrast image, the distance between the X-ray source 4 and the imaging plate 15 is 75 cm or more, and the distance between the imaging table 6 and the imaging plate 15 is 15 cm or more. It is desirable that the distance between the specimen 2 and the distance ratio between the subject 2 and the imaging plate 15 are 1.2 or more and 3.0 or less. Furthermore, refer to Patent Document 2 for details of capturing a phase contrast image.

  Here, the support 10 will be further described with reference to FIG. FIG. 4 is a perspective view showing the support 10 and the members attached to the support 10. As shown in FIG. 4, a fixing member 12 for always fixing the cassette 14 at a predetermined position is disposed on the support base 10. With this fixing member 12, the cassette 14 is mounted at a predetermined position on the support base 10.

  The cassette 14 houses an imaging plate 15 made of a stimulable phosphor exhibiting sensitivity to X-rays. In other words, the cassette 14 is a housing that houses the imaging plate 15, and has a function of preventing physical damage to the imaging plate 15 during transportation or photographing and preventing the imaging plate 15 from being irradiated with light after photographing. Also have.

  Returning to FIG. 2, when the imaging plate 15 accommodated in the cassette 14 shown in FIG. 4 is mounted on the support base 10, the imaging plate 15 faces the lower surface of the imaging base 6 from the X-ray source 4 to the irradiation field. It is positioned so as to include an X-ray irradiation region irradiated through the aperture 5. In addition, the imaging table 6 has an outer frame in which the X-ray irradiation area irradiated through the irradiation field control 5 is made of stainless steel or the like of the imaging table 6. It is positioned so as to include the inner end where the transmission image of the specimen 2 is acquired and the edge of the marker 16 on the subject 2 side.

  The support base 20 supports the imaging unit 3. The support base 20 is provided with a support shaft 21 protruding toward the photographing unit 3, and the photographing unit 3 is fixed to the end of the support shaft 21. With such a configuration, the imaging unit 3 is supported by the support base 20 via the support shaft 21. Further, the support shaft 21 can be moved up and down with respect to the support base 20 and can be rotated around the axis, and the height position and orientation of the photographing unit 3 fixed to the support shaft 21 (rotation around the axis). (Angle) can be adjusted freely.

  The controller 30 operates and controls the operations of the support base 20 and each part of the photographing unit 3. The controller 30 includes a program for controlling each unit of the imaging unit 3, that is, X-ray irradiation, tube voltage of the X-ray source 4 at the time of X-ray irradiation, the vertical position and rotation angle of the imaging unit 3, and the compression plate 7. An imaging program for controlling the vertical position or pressure, data used for the imaging program, and the like are stored.

  The image reading device 40 reads transmission image information of the subject 2 from the imaging plate 15 in the cassette 14 exposed by the X-ray imaging device 1 and stores it as digital image information. When reading the image information from the imaging plate 15, in order to obtain the transmission image information without omission, the image information is read in a wider read image area that reliably covers the transmission image area where the transmission image information exists. Is done. Of course, the read image information includes transmission image information. Further, the image reading device 40 transfers the read image information to the image processing device 50 as output image information.

  The image processing device 50 includes an image processing unit 51, a display unit 52, and an input unit 53, and acquires output image information that is read image information from the image reading device 40 via the communication cable 60. The display unit 52 includes an image display device such as a CRT or LCD, the input unit 53 includes a keyboard and a pointing device, and the image processing unit 51 includes an arithmetic device and a memory. Then, the image processing unit 51 performs image processing such as gradation conversion processing and frequency emphasis processing on the output image information, and displays it on the display unit 52. Here, the position information of the end of the imaging table 6 on the subject 2 side and the position information of the edge of the marker 16 on the subject side are input by the input unit 53. Since both are members fixed on the imaging stand 6, the positional relationship between them is invariable with each imaging. When the marker position is moved and fixed, the input unit 53 updates the position information. Then, the image processing unit 51 performs display image extraction processing for extracting only the display image region from the output image information.

  FIG. 5 is a schematic diagram schematically showing the output image area 80 of the output image information acquired from the image reading device 40. The output image area 80 includes an unnecessary image area 86, a transmission image area 81, and a marker image area 83. The unnecessary image area 86 is an image of a portion of the cassette 14 placed on the support table 10 and located on the subject 2 side. It is an image of the opaque part.

  The transmission image area 81 is an image of an X-ray transmission area including an image of a main part of the subject 2 on the imaging table 6. Here, when the subject 2 is a breast, the subject exists on the unnecessary image region 86 side, and an image of a breast important for diagnosis exists up to the boundary with the unnecessary image region 86. A boundary position between the transparent image area 81 and the unnecessary image area 86 where the breast image exists is referred to as a chest wall position 91.

  The marker image area 83 is an image area of the marker 16 placed on the imaging table 6. The marker 16 is made of a material that does not transmit X-rays, such as stainless steel. Therefore, the marker 16 draws an image of a marginal portion existing on the subject side of the marker 16 at an arrangement position facing the unnecessary image region 86 of the output image region 80, and the position of the marginal portion is represented by the marker boundary. This is referred to as position 90.

  FIG. 1 is a functional block diagram showing a functional configuration when the image processing unit 51 performs display image extraction processing. The image processing unit 51 includes automatic boundary detection means 70, boundary calculation means 71, and display image extraction means 72.

  The display image extraction means 72 cuts out and displays the display image area from the output image area 80 as shown in FIG. A display image area 82 is illustrated in the output image area 80 of FIG. The display image region 82 is a rectangular image region having a predetermined size of about 7000 × 9000 pixels, for example, and is cut out from an image region that is optimal for interpretation by the operator.

  Here, the display boundary position 92 that forms the cut-out position on the subject side of the display image area 82 exactly matches the chest wall position 91 of the transmission image area 81. In FIG. 5, the display boundary position 92 of the display image area 82 and the chest wall position 91 of the transmission image area 81 are displayed with their positions shifted for easy understanding. Since the chest wall position 91 is a diagnostically important part including the transmission image information of the breast, it must be included in the display image area 82. On the other hand, as shown in FIG. When the display boundary position 92 is set at a position deviated, the image of the unnecessary image area 86 with greatly different luminance is mixed in the displayed image of the display image area 82, and for the operator, an image particularly near the chest wall position is displayed. Difficult to interpret.

  Further, the display boundary position 92 of the display image region 82 is determined based on chest wall position information obtained by the automatic boundary detection means 70 or the boundary calculation means 71. Further, the vertical position of the display image area 82 is set to a predetermined position that includes the image of the subject 2 with a margin by arranging the subject 2 at a position on the imaging table 6 specified in advance. The

  The automatic boundary detection means 70 automatically detects the chest wall position 91 of the transmission image area 81 existing in the output image area 80. This detection is performed based on the pixel values of the pixels existing in the output image area 80. That is, since the transmission image area 81 is more likely to transmit X-rays than the marker image area 83 and the unnecessary image area 86, a higher pixel value area is formed compared to the marker image area 83 and the unnecessary image area 86. The region 83 and the unnecessary image region 86 form a low pixel value region because X-ray transmission is small. Accordingly, the pixel value changes rapidly at the marker boundary position 90 and the chest wall position 91. A position where the pixel value changes abruptly, that is, a position where the differential value has a large value is regarded as a boundary.

  Further, this differential value is calculated only for a specific area of the output image area 80, and an efficient boundary detection is performed. FIG. 6 illustrates this specific area. In the vicinity region including the chest wall position 91 and the marker boundary position 90, a chest wall assumed region 84 and a marker assumed region 85 are set. The chest wall assumption area 84 and the marker assumption area 85 are obtained from the assumed positions of the subject 2 placed on the imaging table 6 and surely indicate areas including the chest wall position 91 and the marker boundary position 90.

  Further, a plurality of search lines as shown in FIG. 6 are provided in a direction orthogonal to the chest wall position 91 and the marker boundary position 90 in the output image region 80. A plurality of search lines are set with a certain interval in the chest wall assumption region 84 and the marker assumption region 85 in the output image region 80. Then, the automatic boundary detection means 70 performs differential calculation of the pixel value along the search line, sets the position where the differential value exceeds the threshold as the boundary candidate point of the chest wall position, and determines the chest wall position from this boundary candidate point. . Details will be described in the operation of a chest wall detection process described later.

  Further, the automatic boundary detection means 70 has boundary determination means for determining whether or not the chest wall position information is appropriate based on the chest wall position information of the detected chest wall position. The boundary determination means includes a history storage unit that stores past chest wall position information and a calculation unit that calculates statistical quantities based on the past chest wall position information, such as an average value and variance. The boundary determination unit determines whether the detected chest wall position is appropriate based on a plurality of boundary candidate points of the chest wall position and statistical quantities of the chest wall position. Details will be described in the operation of a chest wall detection process described later.

  The boundary calculation means 71 obtains the marker boundary position from the output image area 80 when the automatic boundary detection means 70 determines that the detection of the chest wall position has failed, and the preset position of the marker 16 on the imaging table 6 Based on the information, the chest wall position is calculated. Here, the marker boundary position is calculated by performing the same method as that used for detecting the chest wall position by the automatic boundary detection means 70 on the assumed marker region 85. Note that the appropriate extracted image region varies depending on the pixel 2 depending on the thickness of the subject 2, so that the chest wall position obtained by the automatic boundary detection means 70 is more accurate than the chest wall position obtained by the boundary calculation means 71. Get higher. Accordingly, when the chest wall position is successfully detected by the automatic boundary detection means 70, it is desirable to perform image extraction based on the chest wall position.

  Next, the operation of the image processing unit 51 will be described with reference to the flowcharts of FIGS. FIG. 7 is a flowchart showing an overall flow of display image extraction processing according to the present embodiment. First, the operator sets the cassette 14 on the support table 10, places the subject 2 on the imaging table 6, and performs imaging using the X-ray imaging apparatus 1 (step S 601).

  Thereafter, the operator removes the cassette 14 from the X-ray imaging apparatus 1, attaches it to the image reading apparatus 40, and reads image information (step S602). Then, the image processing device 50 outputs the read image information thus read as output image information to the image processing unit 51 (step S603). This output image information has an output image area 80 as shown in FIG.

  Thereafter, the image processing unit 51 performs automatic boundary detection processing by the automatic boundary detection means 70 using the output image information (step S604). FIG. 8 is a flowchart showing the operation of the automatic boundary detection process. First, the automatic boundary detection means 70 selects a boundary assumed area from the output image area 80 (step S701). Note that, as for the assumed boundary region, the chest wall assumption region 84 is selected in the case of automatic boundary detection processing, and the marker assumption region 85 is selected in the case of boundary calculation processing described later.

  Thereafter, the automatic boundary detection means 70 performs a boundary candidate point calculation process (step S702). FIG. 9 is a flowchart showing the operation of the boundary candidate point calculation process. First, the automatic boundary detection means 70 extracts pixel values on one search line in the chest wall assumption region 84 (step S801). Then, the pixel value is differentiated at all positions along the search line (step S802). Further, in order to reduce the influence of noise, a configuration can be adopted in which differentiation is performed on a value obtained by integrating a plurality of pixels in a direction perpendicular to the search line.

  Thereafter, the automatic boundary detection means 70 obtains a maximum differential value that is the maximum value of the differentiated pixel values on the search line (step S803). Then, it is determined whether or not the maximum differential value exceeds a preset threshold value (step S804). When the maximum differential value exceeds the threshold value (Yes at Step S804), the automatic boundary detection means 70 stores the pixel position where the maximum differential value exists as a boundary candidate point (Step S805). Further, when the maximum differential value does not exceed the threshold value (No at Step S804), the automatic boundary detecting means 70 proceeds to the next step without performing Step S805.

  Thereafter, the automatic boundary detection means 70 determines whether or not the calculation of the maximum differential value and the determination in step S804 have been performed on all search lines included in the chest wall assumption region 84 (step S806), and is performed on all search lines. If not (No in Step S806), the process proceeds to Step S801, and the maximum differential value is calculated for the remaining search lines and the determination in Step S804 is performed. Further, when the calculation of the maximum differential value and the determination in step S804 are completed for all the search lines (Yes in step S806), the automatic boundary detection means 70 ends the boundary candidate point calculation process, and the automatic boundary detection unit 70 of FIG. Transition to boundary detection processing.

  Thereafter, returning to FIG. 8, the automatic boundary detection means 70 performs boundary determination processing by the boundary determination means (step S703). FIG. 10 is a flowchart showing the operation of the boundary determination process. Here, the automatic boundary detection means 70 uses the boundary candidate points obtained in the boundary candidate point calculation process in step S702 to determine whether the chest wall position has been successfully detected by narrowing down based on a plurality of determination criteria. To do.

  First, the automatic boundary detection means 70 performs determination A for the obtained boundary candidate point (step S901). Here, the judgment A is whether or not the number of those identified as boundary candidate points among the maximum differential values obtained in all the search lines exceeds a predetermined number. If the number of boundary candidate points does not exceed the predetermined number (No at Step S901), the determination information for detecting the chest wall position is set as failure (Step S906), and the process returns to the automatic boundary detection process of FIG.

  In addition, when the number of boundary candidate points exceeds a predetermined number (Yes in step S901), the automatic boundary detection unit 70 performs determination B on the obtained boundary candidate points (step S902). Here, the decision B is whether or not the maximum number of the boundary candidate points between adjacent search lines continuously exceeds a predetermined number. If the maximum number does not exceed the predetermined number (No in step S902), the process proceeds to step S906, where the determination information for detecting the chest wall position is failed, and the process returns to the automatic boundary detection process in FIG.

  Further, when the maximum number exceeds the predetermined number (Yes at Step S902), the automatic boundary detection means 70 performs the determination C on the obtained boundary candidate point (Step S903). Here, the decision C is to determine whether or not the residual square sum of the regression line and the boundary candidate point does not exceed a predetermined number by obtaining a regression line by the least square method using all the boundary candidate points. . If the residual sum of squares exceeds the predetermined number (No at step S903), the process proceeds to step S906, where the determination information for detecting the chest wall position is determined to be failure, and the process returns to the automatic boundary detection process of FIG.

  Further, when the residual sum of squares does not exceed the predetermined number (Yes at Step S903), the automatic boundary detection means 70 performs a determination D on the obtained boundary candidate point (Step S904). Here, the judgment D is the intersection of the regression line obtained in step S903 and the edge of the output image area 80, and whether the intersection position is within a predetermined range by comparing with the past history information. How is it. If the intersection position is not within the predetermined range (No at Step S904), the process proceeds to Step S906, where the determination information for detecting the chest wall position is determined to be failure, and the process returns to the automatic boundary detection process of FIG. The predetermined range when compared with the history information is a range in which the intersection position is predicted to exist with high probability based on statistical quantities such as an average value or standard deviation obtained from the history information of the intersection position. It is. For example, the average value ± predetermined number of pixels, the average value ± (standard deviation × N), and (N: integer) are used as a predetermined range for determination.

  In addition, when the intersection position is within the predetermined range (Yes at Step S904), the automatic boundary detection unit 70 determines that the determination information of the chest wall position is successful (Step S905), and the automatic boundary detection of FIG. Return to processing. The automatic boundary detection means 70 adds / stores the obtained intersection position to the history information to make it the latest. If the intersection position is not stored more than a predetermined number of times as history information, the determination here is not performed and the process proceeds to step S905.

Thereafter, the automatic boundary detection means 70 also ends the automatic boundary detection process of FIG. 8, and returns to the display image extraction process of FIG.
Thereafter, the image processing unit 51 determines whether or not the automatic boundary detection process has failed to detect the chest wall position based on the determination information (step S605). When the chest wall position is successfully detected (No at Step S605), the chest wall position information is transferred from the automatic boundary detection means 70 to the display image extraction means 72 (Step S607). If the detection of the chest wall position fails (Yes at Step S605), the image processing unit 51 performs boundary calculation processing by the boundary calculation unit 71 (Step S606), and obtains chest wall position information from the image information of the marker 16. In step S607, the boundary position information is transferred to the display image extraction unit 72.

  Here, the operation of the boundary calculation process by the boundary calculation means 71 will be described with reference to FIG. FIG. 11 is a flowchart showing the operation of the boundary calculation process. The boundary calculation means 71 selects a marker assumed area 85 from the output image area 80 (step S1001).

  Thereafter, the boundary calculation means 71 performs a boundary candidate point calculation process (step S1002). The operation of this boundary candidate point calculation process is exactly the same as the operation of the boundary candidate point calculation process shown in the flowchart of FIG.

  Thereafter, the boundary calculation means 71 performs a boundary determination process (step S1003). The operation of the boundary determination process is exactly the same as the operation of the boundary determination process shown in the flowchart of FIG. Here, in this boundary determination process, the marker boundary position 90 of the marker 16 is obtained, for example, in the form of the regression line or the intersection of the regression line and the output image region 80. That is, since the marker 16 is made of a material that shields X-rays, such as stainless steel, the difference in pixel value is large and clear at the marker boundary position 90 that is the boundary between the marker image region 83 and the transmission image region 81. Therefore, the determination information does not fail in the determinations A to D in steps S901 to S904 shown in the flowchart of FIG.

  After that, the boundary calculation means 71 uses the marker boundary position shown in FIG. 5 based on the position information of the marker 16 on the imaging table 6 and the end position information on the subject side of the imaging table 6 that are input in advance from the input unit 53. The chest wall position 91 is calculated from 90 (step S1004), and the process proceeds to step S607 in FIG.

  Returning to FIG. 7, the display image extraction means 72 receives the chest wall position information from the automatic boundary detection means 70 or the boundary calculation means 71, and cuts out the display image area 82 (step S608). Here, the display image area 82 cuts out the output image area 80 so that the display boundary position 92 on the unnecessary image area 86 side coincides with the chest wall position 91.

Thereafter, the display image extraction means 72 outputs the image information of the display image area 82 to the display unit 52 for display (step S609), and ends this processing.
As described above, when the automatic boundary detection unit 70 fails in the automatic boundary detection processing of the chest wall position 91 performed when the display image region 82 is cut out from the output image region 80, the boundary calculation unit 71 performs automatic boundary detection processing. The marker boundary position 90 that does not fail is automatically detected, the chest wall position 91 is calculated from the marker boundary position 90 based on the arrangement position information of the marker 16 on the imaging table 6, and the display image region 82 is cut out. Therefore, even when the automatic boundary detection means 70 fails to automatically detect the chest wall position 91, the appropriate chest wall position 91 is surely obtained, and the display image can be easily viewed by the operator.

  In the present embodiment, the marker 16 is a plate having a rectangular shape. However, the shape is not particularly limited, and the marker image shown in the transparent image region 81 allows the position to be specified. If it is a thing, it can also be made into a star shape or other shapes.

  In this embodiment, the case where the imaging plate 15 made of a stimulable phosphor is used as the X-ray image detector is exemplified. However, the scintillator as the X-ray image detector and the optical semiconductor for detecting this emission, CCD A type image sensor or a CMOS type image sensor can also be used. In this case, the image reading device 40 is not necessary, and the X-ray imaging device 1 and the image processing device 50 are directly connected via a communication cable.

  In the present embodiment, the marker boundary position 90 is used when the chest wall position 91 is calculated by the boundary calculation unit 71. However, the marker boundary position 90 is provided by providing the image processing apparatus 50 with the attachment / detachment direction determination unit. It is also possible to detect the attachment / detachment direction of the cassette 14 attached / detached to / from the X-ray imaging apparatus 1. That is, when the cassette direction on the support 10 of the X-ray imaging apparatus 1 or the cassette direction attached to the image reading apparatus 40 is erroneously different by 180 degrees, the detected marker boundary position 90 is also different by 180 degrees. In the example of FIG. 4, the chest wall position 91 and the marker boundary position 90 appear alternately. Here, the marker assumption region 85 and the chest wall assumption region 84 are set at different positions from the lateral edge of the output image region 80 shown in FIG. The cassette attachment / detachment direction can be determined based on the distance between the detected marker boundary or chest wall position and the lateral edge.

  In this case, in FIG. 7, before the automatic boundary detection processing in step S604, first, the boundary calculation processing in step S606 is executed for a marker assumption region that is 180 degrees different from the normal marker assumption region. It recognizes whether it exists at a position or a position different by 180 degrees. Then, the marker boundary position is stored, and thereafter, the processing after step S604 in FIG. 7 is executed. However, if it is determined in step S605 that the detection of the chest wall position in the automatic boundary detection process has failed, the boundary calculation process in step S606 is not performed, and the chest wall position is calculated based on the already stored marker boundary position. With the above procedure, it is possible to extract a target transmission image region regardless of the mounting direction of the cassette 14.

1 is a functional block diagram showing a functional configuration of an image processing apparatus according to an embodiment. It is a block diagram which shows the whole structure of a X-ray imaging system. It is a block diagram which shows the structure of the imaging stand of embodiment. It is a block diagram which shows the structure of the 1st-3rd support stand of embodiment. It is explanatory drawing which shows the structure of the output image area | region of an embodiment (the 1). It is explanatory drawing which shows the structure of the output image area | region of an embodiment (the 2). It is a flowchart which shows the display image extraction process of embodiment. It is a flowchart which shows the automatic boundary detection process of embodiment. It is a flowchart which shows the boundary candidate point calculation process of embodiment. It is a flowchart which shows the boundary determination process of embodiment. It is a flowchart which shows the boundary calculation process of embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray imaging apparatus 2 Subject 3 Imaging | photography part 4 X-ray source 5 Irradiation field squeezing 6 Imaging stand 7 Compression plate 8 Support member 10 Support stand 12 Fixing member 14 Cassette 15 Imaging plate 16 Marker 20 Support base 21 Support axis 30 Controller 40 reading device 50 image processing device 51 image processing unit 52 display unit 53 input unit 60 communication cable 70 automatic boundary detection unit 71 boundary calculation unit 72 display image extraction unit 80 output image region 81 transmission image region 82 display image region 83 marker image region 84 Chest wall assumption area 85 Marker assumption area 86 Unnecessary image area 90 Marker boundary position 91 Chest wall position 92 Display boundary position

Claims (12)

An X-ray imaging apparatus that acquires transmission image information of a subject placed on the imaging table by an X-ray image detector that detects X-rays transmitted through the imaging table;
An image processing apparatus that extracts and displays a display image area consisting only of the transmission image information from output image information of the X-ray imaging apparatus including the transmission image information;
An X-ray imaging system comprising:
The X-ray imaging apparatus has a marker for preventing transmission of the X-ray on the imaging table,
The image processing device automatically detects a boundary position of the transmission image information included in the output image information for the extraction, and the automatic boundary detection unit fails to detect the boundary position. An X-ray imaging system, comprising: boundary calculation means for calculating the boundary position based on marker position information of the marker included in the transmission image information.   The X-ray imaging system according to claim 1, wherein the boundary calculation unit obtains the marker position information using the automatic boundary detection unit.   The X-ray imaging apparatus according to claim 1, wherein the subject is a breast.   The X-ray imaging system according to claim 3, wherein the X-ray imaging apparatus includes phase contrast imaging means for performing phase contrast imaging.   The X-ray imaging system according to claim 3 or 4, wherein the boundary position is a chest wall position located on a chest side of a breast image included in the transmission image information.   6. The X-ray imaging system according to claim 5, wherein the marker is disposed at a position facing the chest wall position on the imaging table.   The X-ray imaging system according to claim 1, wherein the marker is a stainless plate.   The X-ray imaging system according to claim 1, wherein the image processing apparatus includes an input unit that inputs arrangement position information of the marker on the imaging table.   The image processing apparatus includes: a storage unit that stores the boundary position information; and a boundary determination unit that determines the failure based on statistical quantities calculated using history information including the stored boundary position information. The X-ray imaging system according to claim 1, further comprising:   The X-ray imaging system includes an image reading device that reads the imaging plate when a detachable cassette including an imaging plate as the X-ray image detector of the X-ray imaging device is used. The X-ray imaging system according to any one of claims 1 to 9.   The X-ray imaging system according to claim 10, wherein the output image information is read image information read by the image reading device.   12. The X-ray imaging system according to claim 10, wherein the image processing apparatus includes an attachment / detachment direction determination unit that determines an attachment / detachment direction of the cassette based on the marker position information.

Images