JP2005184750A - Radiation digital image processing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To store an interested arena designated for every photographed part and to utilize the arena when the same part is photographed. <P>SOLUTION: A radiation digital image processing system is provided with: an anatomic arena extracting means extracting an anatomic arena of a subject; a position storing means storing a relative position of an arena for every photographed part; and a characteristic amount generating means generating a characteristic amount of a relative position stored by the storing means in the anatomic arena of the subject. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a radiation digital image processing system for processing a radiation digital image, and stores the relative position of a region of interest for each imaging region, and in the case of imaging the same region, the feature amount of the region corresponding to the relative position The present invention relates to an image processing system that uses.

  In recent years, radiation such as X-rays is irradiated on a subject, a radiographic image as a transmission image thereof is directly captured by a solid-state imaging device, and an image signal corresponding to the captured radiographic image is displayed on a CRT (Cathode Ray Tube) display device or the like Developed a radiographic imaging system that displays as a visible image or digitizes the image signal corresponding to the captured radiographic image, performs image processing in the state of digital data, and prints it out Has been.

  In the radiographic imaging system described above, the part to be imaged differs depending on the imaging purpose, and in the image processing performed when the radiographic image is visualized, the region of interest is different for each part to be processed. It is necessary to perform image processing such as density adjustment and contrast adjustment.

  Recently, computer networks are gradually being developed in medical facilities. In addition to the above radiographic imaging system, a radiographic imaging device (CR) and an image intensifier using a stimulable phosphor sheet are also available. Radiation image information photographed by different radiation image photographing devices such as the used radiation image photographing device (II-DR) is processed by the same image processing device, and the processed radiation image information is processed by a CRT display device or a film imager. It may be used in such a way that it is output to a different output device such as a device or a dry printer device.

  In the above case, the operator who operates the image processing apparatus must perform setting operations for a plurality of procedures so that the image processing performed in the image processing apparatus corresponds to each photographing apparatus and output apparatus. In other words, it was very complicated for the operator. Moreover, it is possible to convert the radiographic image data corresponding to the designated area into a density set in advance according to a part, a case, etc. by a cursor designating an arbitrary area of the radiographic image data (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 1-226783

  However, in the above-described invention, it is necessary to designate an area for each photographing with the cursor.

  For example, when the abdomen is imaged, the region of interest is different from the case of a soft tissue such as the intestine or kidney and the case of a bone such as the lumbar vertebra or pelvis. The image processing apparatus is operated so that the operator himself / herself operates an input device such as a mouse or a touch panel so as to perform image processing with different densities and contrasts depending on whether the image is a region of interest. It is necessary to set, and for the operator, these operations are time-consuming.

  The present invention has been made to solve the above-described problems, and is specified for each imaging region in order to automatically perform optimal image processing on a radiation digital image without bothering the operator. It is an object of the present invention to provide a radiation digital image processing system that stores the relative position of the region of interest and uses the feature amount of the region corresponding to the relative position when imaging the same part.

  In order to achieve the above object, a radiological digital image processing system according to the present invention includes an anatomical region extracting means for extracting an anatomical region of a subject, and a position memory for storing a relative position of a region of interest for each imaging region. And a feature quantity generating means for generating a feature quantity of a relative position stored in the storage means in the anatomical region of the subject.

  According to the present invention, in order to automatically perform optimal image processing on a radiation digital image without bothering the operator's hand, the relative position of the region of interest designated for each imaging region is stored, In the case of imaging the same part, it is possible to provide an image processing system that uses a feature amount of a region corresponding to a relative position.

  Hereinafter, the present invention will be described in detail based on a radiation digital image processing system as an embodiment of the present invention.

  FIG. 1 is a diagram showing a schematic configuration of a radiation digital image processing system as an embodiment of the present invention.

  In FIG. 1, 101 is an image data forming unit that outputs radiation digital image data to a subsequent image recording unit 102. The image data forming unit irradiates a subject with radiation such as X-rays, and directly transmits a radiation image as a transmission image thereof. It is a radiographic imaging apparatus which images using radiographing and outputs the radiation digital image data corresponding to the captured radiographic image.

  The image data forming unit 101 is a radiographic image reading apparatus that reads the radiographic image accumulated and recorded on the photostimulable phosphor sheet in addition to the radiographic image capturing apparatus. A radiation image is received by a fluorescent plate, and the received image of the fluorescent plate is converted into radiation digital image data by a solid-state imaging device, or a radiation digital image supplied from a radiation image capturing device connected to a computer network There are input interfaces for inputting data. That is, the image data forming unit 101 itself does not have to be a radiographic image capturing apparatus. For example, radiographic image data indicating a radiographic image captured by a radiographic image capturing apparatus installed in a remote hospital or the like is stored on the Internet or the like. It may be configured to be input to the digital radiographic image processing system via the computer network.

  An image data recording unit 102 records digital radiation image data output from the image data forming unit 101. The image data recording unit 102 includes, for example, a semiconductor memory or a hard disk drive that can write data at high speed.

  Reference numeral 103 denotes an anatomical extraction unit that analyzes the digital radiographic image data stored in the image data recording unit 102 based on the part information specified in the subsequent part specification unit 106 and extracts an anatomical image region. .

  A position storage unit 104 stores the relative position of the region of interest designated by the position designation unit 107 in the subsequent stage for each part.

  Reference numeral 105 denotes a feature amount generation unit that generates information about the feature amount used for image processing of the subsequent image processing unit 108 from the anatomical region of the anatomical region specifying unit 103 and the relative position information from the position storage unit 104. It is.

  Information on the feature amount includes a maximum value, a minimum value, an average value, a median value, a mode value, and the like of pixel values in an area corresponding to a relative position.

  Based on the information related to the feature quantity of the feature quantity generation unit 105, 108 performs image processing on the radiation digital image data recorded in the image recording unit 102 so that the region of interest has an optimal density and / or gradation. Apply.

  An image transfer unit 109 adds a header to the image data processed by the image processing unit 108 and transfers the image data to the film imager 111 or the like via the network 110. As image data header, image data such as image ID, imaging date / time, imaging region, tube voltage, tube current, exposure time, etc., serial number of image data forming unit used for imaging, grid type, etc. Information on the forming unit, patient information such as patient ID, patient name, date of birth, sex, etc., information such as the number of pixels in the horizontal direction, the number of pixels in the vertical direction, the number of bits in the image, and the pixel pitch.

  This system is roughly divided into two steps. One is a step of storing a region of interest for each part, and the other is a step of performing image processing based on the stored region of interest.

  Regarding the step of storing the region of interest for each part, an example of storing the region of interest of the abdomen based on FIGS. 2 to 6 will be described. FIG. 2 shows the flow of this process. FIG. 3 is a diagram illustrating an example of the site designation unit 106. In this example, it is a part of the control unit 301 that operates the image data forming unit 101. As the control unit 301, for example, a touch panel configured by a liquid crystal display and an analog resistive film type touch sensor sheet is applied. The control unit 301 can display a photographed image 302 after photographing. The actual imaging conditions are also displayed on the imaging condition display 303 from the X-ray generation means. In addition, patient information 304 such as the patient's name, sex, and age is displayed. The part designating unit 106 includes buttons 305 classified by photographing parts such as a head and a neck. The operator selects the button 305 of the part designating unit 106 as a part to be photographed. In this example, the “abdomen” button is pressed.

  FIG. 4 shows an abdominal radiation image. The abdominal image can be divided into two areas, a subject area and a non-subject area, a so-called “skull” 403. The subject area can be broadly classified into a soft tissue 401 including the intestines and kidneys and a bone 402 such as the spine and pelvis.

  FIG. 5 shows a histogram of each pixel value of the abdomen image.

  The histogram is roughly divided into two peaks. A mountain having a lower pixel value is a mountain 501 in the subject area, and a mountain having a higher pixel value is a hollow mountain 502. Of the peaks 501 in the subject area, the lower pixel value, that is, the threshold T1 or less corresponds to the bone portion. The higher pixel value of the mountain 501 of the subject area, that is, the skirt (on the right side) of the threshold value T1 to T2 is equivalent to the soft tissue.

  The position storage unit 104 stores the region of interest specified by the position specifying unit 107 as a relative position. When the image data forming unit is a solid-state image sensor, this relative position may be a position in a coordinate system with the corner of the solid-state image sensor as the origin, or a coordinate system with the center of the solid-state image sensor as the origin. Also, a coordinate system with the center of gravity of the subject area as the origin may be used. In this example, a coordinate system with the center of gravity of the subject area as the origin is described.

  First, as described above, the histogram is analyzed to divide the region into a subject region and a non-subject region. Then, a process of setting the pixel value of the non-subject area to 0 is performed. The result of this processing is shown in FIG. A hatched portion 601 is a region where the pixel value is zero.

  Next, the barycentric coordinates of the subject area are obtained. When the image size is M × N and the image data is f (x, y), the barycentric coordinates Org_x and Org_y are obtained by the following equations.

Org_x = (1)
Org_y = (2)
However, when = 0 = 0,
When = 1> 0,
The obtained center-of-gravity coordinates Org_x and Org_y are used as the origin.

  Furthermore, in the subject region, the region is divided into a bone portion and a soft tissue by analyzing the histogram. In each divided area, a process for setting the pixel value outside the area to 0 is performed. The result of this processing is shown in FIG. 7 for soft tissue and FIG. 8 for bone. Here, 701, 801, and 802 indicate areas outside the region.

  FIG. 9 is a diagram illustrating an example of the position specifying unit 107.

  For example, the position specifying unit 107 is a screen that displays a part of the captured image of the control unit 601 described above. The position is designated by selecting a region of interest on the captured image on the touch panel. If one point is designated on the touch panel, an area having a certain size is surrounded by a frame 901. Alternatively, by specifying two points, the upper right and lower left corners may be determined, and a rectangular area may be determined. Although it is rectangular in FIG. 9, it may be circular.

  Next, it is determined whether the portion specified by the position specifying unit 107 is included in the bone portion or the soft tissue region.

  After calculating which coordinate on the image data corresponds to the portion specified by the position specifying unit 107, it is determined whether the coordinate is included in the bone portion or the soft tissue region.

  The position storage unit 104 stores, for example, the relative position of the rectangular region, the size of the rectangular region, and the bone region or the soft tissue region. In this example, since there is a rectangle in the range displayed in FIG. 7, it is determined that the soft tissue is designated. The position storage unit 104 may repeat this process for a plurality of photographed data and store an average value of relative positions. The relative position may be normalized by the size of the subject area. That is, for a subject larger than the average subject size, the relative position may be far from the origin position, and conversely, when the subject is small, the origin position may be approached.

  A process of performing image processing based on the region of interest stored based on FIG. 10 will be described.

  First, the position specifying unit 106 selects a part to be imaged. In this example, the “abdomen” button is pressed.

  As described above, first, the histogram is analyzed to divide the region into the subject region and the non-subject region, the barycentric coordinates of the subject region are obtained, and the origin is calculated.

  Next, in the subject region, the histogram is analyzed to divide the region into bone and soft tissue to obtain the soft tissue region.

  The region of interest is a region where the relative position of the rectangular region of “abdomen” stored in the position storage unit 104 overlaps with the soft tissue region or a region close thereto. When the relative position is normalized by the subject size, the photographed subject is compared with the average subject, and when the subject size is significantly different from the average size, the relative position is corrected and calculated.

  In the feature quantity generation unit 105, for example, a total addition value is calculated by adding all the pixel values in the region of interest, and an average is obtained by dividing the calculated total addition value by the number of pixels in the image region in the region of interest. A value A is calculated and output to the image processing unit 108.

  In this example, since the imaging region is selected as “abdomen” in the region designating unit 106, the average value A supplied as information on the feature amount from the feature amount generating unit 105 is the final value A in the image processing unit 108. In particular, density conversion processing is performed based on a density conversion curve having density conversion characteristics such that an optimum density value D is obtained on the film output from the film imager 111.

  The image processing unit 108 includes a look-up table (hereinafter simply abbreviated as LUT) in which a plurality of types of data indicating density conversion curves serving as a reference for density conversion processing are stored for each imaging region. Data relating to the density conversion curve corresponding to the imaging region selected in is read from the LUT. That is, in the case of this example, data indicating a density conversion curve for “abdomen” having density conversion characteristics as indicated by a thick line in FIG. 11 is automatically read from the LUT.

  Then, the image processing unit 108 translates the density conversion curve indicated by the data read from the LUT so that the average value A calculated by the feature value generation unit 105 becomes the density value D, and actually converts the density. The correction is made to a density conversion curve using processing (a density conversion curve having density conversion characteristics as shown by a thin line in FIG. 11).

  Further, the image processing unit 108 performs density conversion processing on the radiation digital image indicated by the radiation digital image data obtained by imaging the abdomen of the patient output from the image recording unit 102 in accordance with the corrected density conversion curve, and then performs density conversion. Radiation digital image data subjected to the conversion process is supplied to the image transfer unit 109.

  In the film imager 111 or the like to which image data has been transferred, the radiation digital image is printed on the film at a laser intensity corresponding to the pixel value indicated by the radiation digital image data supplied from the image transfer unit 109. It becomes possible to form a radiological digital image of density.

  In the above-described operation example, the case where the imaging region is the “abdomen” has been described as an example. However, for example, when the imaging region is the “chest”, the histogram of the subject region is analyzed and the lung field portion and the mediastinum are analyzed. The area of the lung field is obtained by dividing the area into other areas such as the head and subdiaphragm. A region of interest is defined as a region where the relative position of the rectangular region of “chest” stored in the position storage unit 104 overlaps with the lung field region. A feature amount in the region of interest is calculated, and density conversion processing is performed.

  The present invention may be used for an image processing system that stores the relative position of a region of interest for each imaging region and uses the feature amount of the region corresponding to the relative position when imaging the same region.

It is a figure which shows an example of the structure of the radiation digital image processing system which concerns on this invention. It is a flowchart explaining an example of the process in the radiation digital image processing system which concerns on this invention. It is the figure which showed an example of the operation screen of the radiation digital image processing system which concerns on this invention. It is the figure which expanded and showed the part of the to-be-photographed object display area which concerns on embodiment of this invention. It is the figure which showed the histogram of the to-be-photographed object which concerns on embodiment of this invention. It is the figure which showed having remove | excluded except the subject display area which concerns on embodiment of this invention. It is the figure which showed the soft tissue area | region of the to-be-photographed object which concerns on embodiment of this invention. It is the figure which showed the bone | frame part area | region of the to-be-photographed object which concerns on embodiment of this invention. It is the figure which showed the position designation | designated part which concerns on embodiment of this invention. It is a flowchart explaining an example of the process in the radiation digital image processing system which concerns on embodiment of this invention. It is the figure which showed the lookup table which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Image data formation part 102 Image recording part 103 Anatomical area | region extraction part 104 Position memory | storage part 105 Feature-value production | generation part 106 Site designation | designated part 107 Position designation part 108 Image processing part 109 Image transfer part 110 Network 111 Film imager

Claims (1)

  An anatomical region extracting means for extracting the anatomical region of the subject, a position storage means for storing the relative position of the region of interest for each imaging region, and a relative position stored in the storage means in the anatomical region of the subject A radiation digital image processing system comprising: a feature amount generating unit configured to generate a feature amount.

Images