JP2000275761A - Radiation image connecting and processing method and radiation image processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make accurately alignable radiation images respectively recorded on plural sheets which are connected so that the sheets may partly overlap each other, and to make reconstitutable the images. SOLUTION: The radiation image P of an object is recorded across two stimulabe phosphor sheets 31 and 32 which are connected so that they may partly overlap each other, and among two radiation images obtained and from respective stimulable phosphor sheets 31 and 32, a template T is set in the overlapping area of the 2nd radiation image by a template setting means 12, and an area coinciding with the template is searched in the overlapping area of the 1st radiation image by a template coinciding means 13, then, the alignment is executed by an aligning means 14 so that the template may coincide with the area, and one radiation image P is reconstituted by a reconstituting means 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiographic image connection processing method and a radiographic image processing apparatus, and more particularly to a method for reconstructing a radiographic image of a subject recorded by connecting a plurality of stimulable phosphor sheets. Is related to image connection processing.

[0002]

2. Description of the Related Art In recent years, CR (Computed Radiograph) has been used to obtain a radiation image over an extremely wide radiation exposure area.
hy) The system is widely used. This CR system accumulates part of this radiation energy when irradiated with radiation (X-ray, α-ray, β-ray, γ-ray, electron beam, ultraviolet ray, etc.), and then accumulates when irradiated with excitation light such as visible light. The radiation image information of the subject such as the human body is temporarily recorded on the stimulable phosphor sheet that shows stimulated emission according to the energy that has been emitted,
The sheet on which the radiation image is recorded is scanned with excitation light such as a laser beam to generate stimulated emission light corresponding to image information as signal light, and the emitted stimulated emission light is photoelectrically read by a photomultiplier or the like. Means for reading an image signal, and based on the image signal, a recording medium such as a photographic photosensitive material;
This system outputs a radiation image of a subject as a visible image on a display device such as a CRT (Japanese Patent Laid-Open Nos.
-11395 and 56-11397).

The stimulable phosphor sheet used in this CR system has conventionally been prepared in half-cut, large-angle, four-cut, six-cut, etc. sizes depending on the object to be photographed. In many cases, it is often desired to observe a long image from the neck to the waist as a single image in order to measure the degree of curvature of the spine, and the long image is longer in a certain direction than the size described above. The use of a stimulable phosphor sheet has been studied.

However, a radiation image reading apparatus that reads image information from a stimulable phosphor sheet needs to be redesigned, including a sheet conveying path, so as to be adapted to such a long sheet. Since it is dedicated, it is disadvantageous in terms of cost.

Therefore, two sheets of the conventional size are connected to form an apparently long sheet, and the long image is photographed and recorded on the apparently long sheet, and is read one by one at the time of reading. By doing so, reading can be performed using an existing radiation image reading apparatus, and the above-described problem does not occur.

In this method, three or more stimulable phosphor sheets are connected to each other to photograph and record a longer object.
A wide and long image of the subject can be photographed and recorded by connecting the sheets in two orthogonal directions, and the adaptability according to the subject is excellent.

[0007]

When two or more sheets are successively photographed and recorded as described above, if attention is paid to two adjacent sheets among the plurality of consecutive sheets, the sheet There is a method in which the edges of the two sheets are connected to each other, or a method in which a part of two sheets are overlapped and connected. However, in the method in which the edges are connected and connected, an image is lost at the boundary. I have no choice. On the other hand, in a method in which a part of two sheets is overlapped and connected, no loss occurs in recording of such an image.

However, in a system in which a part of two sheets is overlapped and connected, two radiation images read from the two sheets are simply connected without a gap.
Since an image of an overlapping portion is recorded in each of the images, a normal radiation image of the subject cannot be reconstructed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to accurately realign radiographic images recorded on a plurality of sheets in which a part of the sheets are overlapped and connected. It is an object of the present invention to provide a radiographic image connection processing method and a radiographic image processing apparatus which can perform the above.

[0010]

SUMMARY OF THE INVENTION According to the present invention, there is provided a radiographic image linking processing method and a radiographic image processing apparatus for linking radiographic images recorded on two mutually adjacent stimulable phosphor sheets. The two radiation images are aligned by performing template matching on the radiation image portions recorded in the overlapping portions of the two stimulable phosphor sheets, respectively.

That is, in the method of linking radiographic images according to the present invention, an object is formed over a plurality of stimulable phosphor sheets in which a part of two adjacent stimulable phosphor sheets are connected so as to overlap each other. When one radiation image is recorded and a plurality of radiation images obtained by individually reading from each of the plurality of stimulable phosphor sheets are subjected to a linking process so as to reconstruct the one radiation image, A radiation image obtained by reading from any one of the two stimulable phosphor sheets adjacent to the stimulable phosphor sheet in an overlapping area corresponding to an overlapping portion with the other stimulable phosphor sheet. At least one or more regions are set as a template, and a radiation image obtained by reading from the other stimulable phosphor sheet is compared with the one stimulable phosphor sheet. Searching for an area that matches the template in the overlapping area corresponding to the multiple portions, and performing positioning of the two radiographic images so that the area obtained by the search matches the template. It is assumed that.

In the following, of the two stimulable phosphor sheets where the two stimulable phosphor sheets overlap each other, the sheet farther from the subject is referred to as the first stimulable phosphor sheet and the sheet closer to the subject is referred to as the first stimulable phosphor sheet. It is referred to as a second stimulable phosphor sheet, and a radiation image obtained by reading from the first stimulable phosphor sheet is obtained by reading from the first radiation image and the second stimulable phosphor sheet. The radiation image is referred to as a second radiation image.

The phrase "one radiographic image of a subject is recorded" does not mean that "one subject is recorded" but means "one image is recorded as an image including the background of the subject". .

The number of templates to be set may be only one or two or more. However, setting a plurality of templates can enhance the reliability of positioning, and
preferable. When setting a plurality of templates, mutually different areas in the overlapping area are set as templates, and when searching for an area that matches each template, the plurality of templates are maintained while maintaining the positional relationship of the plurality of templates in the radiation image. A plurality of regions are searched so that the templates of the radiation images match at the same time, and when the two radiation images are aligned, all of the templates of one radiation image and the regions of the other radiation image match at the same time. Then, the alignment may be performed.

The template is set in the overlapping area of the first radiation image, and within the overlapping area of the second radiation image,
A region that matches this template may be searched for the region. Conversely, the template may be set as an overlapping region in the second radiographic image, and the template may be set in the overlapping region of the first radiographic image. Although an area to be searched may be searched for, a feature image is automatically detected in the overlapping area as described later, and a template is automatically set based on the detected feature image. Since the feature image can be more accurately detected from the second radiation image having a relatively large irradiation dose, it is preferable to set a template in an overlapping area of the second radiation image.

The overlapping area is detected by detecting a boundary image of a portion overlapping with the second stimulable phosphor sheet in the first radiographic image, and detecting based on the detected boundary image. This is preferable in that processing is simplified. Specifically, the detection of the boundary image may be performed by performing an edge detection process such as a differentiation process on the radiation image data representing the first radiation image. Show.

That is, in the overlapping portion, since the first stimulable phosphor sheet is covered by the second stimulable phosphor sheet, the overlapping portion of the first stimulable phosphor sheet has a larger area than the non-overlapping portion. A small dose of radiation is delivered. Therefore, in the first radiographic image obtained by reading from the first stimulable phosphor sheet, the image density is set between the overlapping region corresponding to the overlapping portion of the sheet and the non-overlapping region corresponding to the non-overlapping portion. (This is a general term representing the level of light and shade, light and dark, etc. in an image having a gradation, and also includes the meaning as luminance in a display device such as a CRT. When a radiation image is expressed as an image signal, Represents an image signal value (image data)). As a result, a boundary line image is formed between the two regions due to the density difference. This boundary line image can be detected, for example, by performing edge detection processing such as differentiation processing on image data representing the first radiation image along the connection direction of the two sheets.

After the boundary image in the first radiographic image is detected in this manner, an area extending from this boundary image to the edge of the image on the side of the overlap area is overlapped in the first radiographic image. It can be recognized as an area. on the other hand,
For the second radiographic image, from the edge on the overlap region side,
The range of the length from the boundary image in the first radiographic image to the edge on the overlapping area side may be recognized as the overlapping area. When reading a radiation image from the stimulable phosphor sheet, if the image recorded at the edge of the sheet can be completely read, the first image is read as described above.
If the overlap area in the radiation image of the second sheet completely coincides with the overlap area in the second radiation image, but the image recorded on the edge of the sheet cannot be completely read, the edge of the second sheet Therefore, since the position corresponding to the length that cannot be read becomes the edge of the second radiation image, the overlap region in the first radiation image does not always coincide with the overlap region in the second radiation image. In some cases, the overlap area in the second radiation image may be smaller than the overlap area in the first radiation image by the length that cannot be read. Therefore, a range of a length obtained by subtracting the length from the edge of the second radiographic image on the overlapping region side by the unreadable length may be recognized as the overlapping region.

The template set in the overlapping area of any one of the radiation images may be any area in the overlapping area, but the area including the characteristic image in the overlapping area is determined by template matching. It is preferable from the viewpoint of the accuracy of the above.

Here, the characteristic image means, for example, that when radiography is performed after a positioning marker formed of a material having a very low radiation transmittance is arranged in advance in the overlapping portion of the sheet, An image of this marker that appeared in each overlapping region of the image, a bone portion having a characteristic shape that appeared as an image of the subject itself (particularly, an edge portion of this image portion),
An image portion where ribs intersect each other (particularly, an edge portion of this image portion), a lung field portion (particularly, an edge portion of this image portion), and the like can be applied.

The feature image in the overlapping area may be automatically detected based on the image (corresponding radiation image data) in the overlapping area, or may be detected by an operator and detected. May be automatically set based on the detected characteristic image, or may be set manually by the operator. However, it is preferable that both are performed automatically in order to reduce the work of the operator. When automatically detecting a feature image, a detection algorithm for detecting a predetermined image portion as a feature image is stored in advance,
What is necessary is just to make it detect automatically according to this algorithm, and the automatic setting of a template sets the local area | region of a predetermined shape (rectangular, circular, etc.) including the vicinity area | region of the detected characteristic image as a template. A template setting algorithm may be stored in advance and automatically set according to the algorithm.

In the overlapping area, the second radiation image read from the second stimulable phosphor sheet near the subject is read from the first stimulable phosphor sheet far from the subject. It is preferable to perform the connection processing by overwriting the first radiation image. As described above, the overlapping portion of the first sheet has a smaller radiation arrival dose than the non-overlapping portion. Therefore, when the first radiation image obtained from this sheet is used, the image is added to the connected portion of the two images. This is because, when the image of the second sheet is used, the density difference between the images does not occur at the connected portion of the two images.

However, if the image recorded on the edge of the sheet cannot be completely read, when the two images are aligned, only the length that cannot be read from the edge of the sheet is used. Since the position of the edge of the second radiation image does not match the position of the boundary image of the first radiation image, an image of a sheet farther from the subject is used for an area of a length that cannot be read. I have no choice. In this case, in the reconstructed radiographic image after linking, the density becomes lower than that of the other portions only in the region of the unreadable length. Correction such as uniformly shifting the density value may be performed so that the density substantially matches the density of the radiation image of the portion that is not present.

When it is assumed that the density correction is performed in this way, as described above, the present invention is not limited to the method in which the second radiographic image is overwritten on the first radiographic image to perform the connection processing. Conversely, the first radiographic image is
May be overwritten on the radiographic image and subjected to the linking process. There is a substantial difference in the time required for the correction process between performing the density correction for only a part of the overlapping portion (the area of a length that cannot be read) and performing the density correction for the entire overlapping portion. Because there is no. However, since the first radiation image in the overlapping area has a smaller arrival dose than the second radiation image, it is inferior to the second radiation image in terms of granularity (noise). Therefore, it is preferable to use the second radiographic image as much as possible.

In a shooting and recording operation for storing and recording an image of a subject on the stimulable phosphor sheet, since the radiation spreads out from the radiation source and emits radiation, the first stimulable phosphor sheet farther from the subject and the subject The size of the image of the subject to be recorded is slightly different between the second stimulable phosphor sheet and the second stimulable phosphor sheet close to the second stimulable phosphor sheet, and the size of the first radiation image is larger than that of the second radiation image. For this reason, in the reconstructed image, if the difference in size between the two radiographic images before the consolidation processing adversely affects observation and interpretation, the first radiographic image and / or the second radiographic image are compared with each other. The size of both radiographic images may be made to match by performing a scaling process.

[0027] Of the two radiation images obtained by reading from the two stimulable phosphor sheets, respectively, the radiation image obtained by reading from the sheet farther from the subject or the radiation image obtained by reading from the sheet closer to the subject is used. If it is not possible to specify in advance whether the image is a radiation image obtained by reading, an edge detection process is performed on each of the two radiation image data representing the two radiation images, and based on the result of the edge detection process. Which of the two radiation images is read from a sheet farther from the subject (first radiation image) or a radiation image read from a sheet closer to the subject (second radiation image). It is preferable to specify whether the image is a radiation image).

In this case, when the total number of stimulable phosphor sheets connected is two, the boundary line image appears only in one of the radiation images. Therefore, the boundary line image is detected by the edge detection processing. The radiation image on the other side is a radiation image read from the stimulable phosphor sheet on the side farther from the subject, and the radiation image on which the boundary image is not detected is from the stimulable phosphor sheet on the side closer to the subject. It is possible to specify that the radiation image has been read. In the case where the number of stimulable phosphor sheets connected is more than two, the radiographic image obtained by reading from the sheet farther from the subject or the sheet closer to the subject is obtained simply by the presence or absence of the boundary image. Although it is not possible to specify whether the image is a radiation image obtained by reading from a sheet, the overlapping portion between two adjacent sheets can be limited within a limited range of the sheet, and thus the limited Within the range
Since the boundary image appears only in one of the radiation images, the edge detection process allows the radiation image in which the boundary image is detected to be the radiation image read from the stimulable phosphor sheet on the far side from the subject. Yes, it is possible to specify that the radiation image for which no boundary image is detected is a radiation image read from the stimulable phosphor sheet on the side closer to the subject.

The radiographic image processing apparatus of the present invention is an apparatus for performing the radiographic image linking processing method of the present invention, such that a part of two adjacent stimulable phosphor sheets overlap each other. A radiation image of the subject is recorded over the plurality of stimulable phosphor sheets connected to each other, and a plurality of radiation images obtained by reading each of the plurality of stimulable phosphor sheets are separately read from the subject. A radiation image processing apparatus provided with a connection processing means for performing a connection processing so as to reconstruct the radiation image of the above-mentioned, by reading from one of the two stimulable phosphor sheets of the adjacent two stimulable phosphor sheets. Template setting for setting at least one or more of the overlapping regions of the obtained radiation image corresponding to the overlapping portion with the other stimulable phosphor sheet as a template Means for searching for an area matching the template in an overlapping area corresponding to an overlapping part of the one stimulable phosphor sheet of the radiographic image obtained by reading from the other stimulable phosphor sheet. It is characterized by comprising template matching means, and positioning means for positioning the two radiographic images so that the area obtained by the search matches the template.

Here, the number of templates set by the template setting means may be one or two or more. The use of a plurality of templates enhances the reliability of positioning. It is preferable in that it can be performed.

Also, in the first radiographic image obtained by reading from the first stimulable phosphor sheet farther from the subject, the boundary of the overlapping portion with the second stimulable phosphor sheet closer to the subject. A line image is detected, and an overlapping area in each of the first radiation image and the second radiation image obtained by reading from the second stimulable phosphor sheet is detected based on the detected boundary image. It is preferable to further include an overlapping area detecting unit. In this case, it is preferable that the overlapping area detecting means detects the boundary image by performing an edge detection process on the radiation image data representing the first radiation image.

Preferably, the template setting means sets an area including the characteristic image in the overlapping area of the radiation images as a template.

Further, the template setting means automatically detects a feature image based on an image in an overlapping area in the radiation image, and automatically sets a template based on the detected feature image. But,
It is desirable from the viewpoint of reducing the work of the operator.

The connection processing means overwrites the first radiographic image with the second radiographic image for the overlapping area, and performs the consolidation process on the first radiographic image and the second radiographic image. This is preferable in that the density of the radiation image obtained by the connection processing can be made uniform.

[0034] Of the two radiation images obtained by reading from the two stimulable phosphor sheets, respectively, the radiation image obtained by reading from the sheet farther from the subject or the radiation image obtained by reading from the sheet closer to the subject is used. If it is not possible to specify in advance whether the image is a radiation image obtained by reading, an edge detection process is performed on each of the two radiation image data representing these two radiation images, and based on the result of the edge detection process, Which of the two radiation images is a radiation image (first radiation image) obtained by reading from a sheet far from the subject or a radiation image (second radiation image) obtained by reading from a sheet near the subject It is preferable from the viewpoint of automatic processing to employ a configuration further including a radiation image specifying unit for specifying whether the image is a radiation image).

[0035]

According to the radiographic image connection processing method and the radiographic image processing apparatus of the present invention, radiation obtained by reading from one of the two adjacent stimulable phosphor sheets is obtained. At least one in an overlapping area of the image corresponding to the overlapping portion with the other stimulable phosphor sheet.
One area is set as a template, and in a radiation image obtained by reading from the other stimulable phosphor sheet, an area corresponding to this template in an overlapping area corresponding to an overlapping part with one stimulable phosphor sheet Is searched and the two radiation images are aligned so that the region obtained by the search matches the template. Therefore, unlike the case where the two radiation images are simply connected without a gap, the alignment is performed with high accuracy. Can be performed, so that a regular radiographic image can be reconstructed.

Further, since the template matching is performed in a limited area only in the overlapping area, the time required for the template matching process can be shortened. Further, since the template matching is performed in such a narrow area, the accuracy of the template matching can be reduced. Can be enhanced.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment of a radiographic image processing apparatus for implementing a radiographic image linking method according to the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of a radiation image processing apparatus for carrying out the radiation image connection processing method of the present invention. FIG. 2 is a diagram showing two stimulable phosphor sheets partially overlapping each other. FIG. 3 is a diagram illustrating a state in which one radiation image of a subject is recorded. FIG. 3 is a diagram illustrating the state in which the radiation image processing apparatus illustrated in FIG. 1 is read from the two stimulable phosphor sheets illustrated in FIG. It is a figure showing two radiation images processed.

The radiation image processing apparatus shown in FIG.
A part of the stimulable phosphor sheets 31 and 32 are connected so as to overlap each other, and a radiation image P of the subject is recorded over both sheets 31 and 32 as shown in FIG. Two radiation images P1 and P2 obtained by reading each of the stimulable phosphor sheets 31 and 32 respectively.
Is a radiation image processing apparatus that performs a concatenation process on the radiation image data S1 and S2 respectively representing the two radiation images P1 and P2 so as to reconstruct the radiation image P of the subject. It is obtained by reading from the overlapping area detecting means 11 for detecting the overlapping area of both radiation images P1 and P2 corresponding to the overlapping part of 32, and the second stimulable phosphor sheet 32 arranged on the side closer to the subject. Template setting means 12 for setting a rectangular area including the characteristic image X recorded in the overlapping area detected by the overlapping area detecting means 11 of the second radiation image P2 as a template T; The first radiation image P1 obtained by reading from the body sheet 31 matches the template T within the overlapping area detected by the overlapping area detecting means 11. 'And template matching unit 13 for searching a searched area T' obtained frequency T so as to coincide with the template T, the first radiographic image P1
And a second radiation image P2, a positioning means 14 for positioning the two radiation images P1 and P2 (data S1 and S2 of the two radiation images P1 and P2 aligned by the positioning means 14).
Is connected to (a data S of) the radiation image P and output.

Here, the overlapping area detecting means 11 uses the first radiation image P1 based on the first radiation image data S1.
Image 1 of the overlapped portion with the second sheet 32, which is shown in FIG.
c, and the boundary image 1 of the first radiation image P1 is detected.
c, the range of the distance L from the overlapping area side edge (lower edge) 1b is detected as the overlapping area, while the second radiation image P
The range of the distance L from the edge 2a of the overlapping region (upper edge) 2a to the boundary 1c of the first radiation image P1 to the edge 1b of the overlapping region is detected as the overlapping region.

Based on the first radiation image data S1,
Detection of the boundary image 1c appearing in the first radiation image P1 is as follows.
The filter f of 8 pixels vertically × 1 pixel horizontally shown in FIG.
The first radiographic image P1 shown in FIG. 1A is moved one pixel at a time along the arrow X direction (the direction orthogonal to the connecting direction (the arrow Y direction) of both images P1 and P2), and for each movement,
First pixel k1, fourth pixel k2, fifth pixel k of filter f
Third, the value of the image data S1 of the radiation image P1 corresponding to the eighth pixel k4 (hereinafter, the value of the image data S1 corresponding to k1 corresponds to K1, the value of the image data S1 corresponding to k2 corresponds to K2, k3) The value of the image data S1 is K3, k4
Is calculated according to the following logical expression (1).

If ((K1> K4) and (K2> K)) then M = M + 1 else if ((K1 <K4) and (K2 <K3)) then M = M-1 else M = M ± 0 (1) This logical expression indicates that the data value K1 of the first pixel k1 is larger than the data value K4 of the eighth pixel k4 (that is, the density is higher) and the data value K2 of the fourth pixel k2 is the fifth pixel k3
If the data value K3 is larger than the data value K3 (the density is high), there is a high possibility that the boundary line image 1c having a large density variation exists between the fourth pixel k2 and the fifth pixel k3. +1 "each, while the data value K of the first pixel k1 is
1 is smaller than the data value K4 of the eighth pixel k4, and the data value K2 of the fourth pixel k2 is the data value K of the fifth pixel k3.
When the value is smaller than 3, since the density is reversed from that of the boundary image 1c, the evaluation value M is added by “−1”, and in other cases, the evaluation value M is not changed (M = ± 0).

The evaluation value M when the filter f is moved from one side edge to the other side edge along the X direction.
Is the evaluation value M of the line (the line extending in the X direction).

Next, the above operation is repeated by moving the filter f by one pixel in the direction of arrow Y, and an evaluation value M for a line shifted by one pixel is obtained. Hereinafter, similarly, the filter is moved one pixel at a time in the Y direction to obtain the evaluation value M of each line, and the fourth pixel k2 and the fifth pixel k3 of the filter f in the line where the evaluation value is positive and the maximum value It can be said that there is a boundary image between.

However, the boundary image 1 by this algorithm
The detection of c is very effective when the boundary image 1c appears as being substantially parallel to the upper edge or the lower edge 1b of the radiation image P1, but the boundary image 1c is detected as the upper edge or the lower edge 1b. , The evaluation value M has the same value over several lines, and the boundary image 1c cannot be specified.

In the case where the boundary image 1c has an inclination as described above, the evaluation value M is within a range of several lines in which the same value is shown, and furthermore, at each one position near the left and right side edges of the radiation image P1. The boundary image 1c may be detected by searching for the boundary image 1c and connecting the boundary images 1c detected near the left and right side edges with straight lines.

In the above-described filter f, edge detection is performed by differential processing in which evaluation is made only based on the difference (K2−K3) between the data values K2 and K3 between two adjacent pixels of the fourth pixel k2 and the fifth pixel k3. Although it is possible to do this, it is susceptible to the effects of noise and the recorded image itself,
By performing the evaluation using the vertically long filter f as described above, the boundary image 1c can be accurately detected.

However, such edge detection is not excluded, and the density (radiation image data S1) gradient between two adjacent pixels of the first radiation image P1 is moved one by one in the arrow Y direction. Then, two adjacent pixels in which the density of the upper pixel in the figure is higher than the density of the lower pixel are obtained as candidates for the existence position of the boundary image, and the search in the direction of the arrow is performed by setting the search position in the direction orthogonal to the arrow. The same operation is performed after moving one pixel at a time, and a method of detecting, as the boundary line image 1c, a line in which the candidate for the existing position of the boundary line image 1c is distributed in the X direction substantially orthogonal to the arrow, or a Hough transform May be used to detect the boundary image 1c.

The template setting means 12 generates a characteristic image (bone part having a characteristic shape (particularly, the image part) of the second radiation image P2, which is recorded in the overlapping area detected by the overlapping area detecting means 11. Edge part), image part where ribs cross each other (especially edge part of this image part)
And a detection algorithm set to automatically detect a lung field portion (particularly, an edge portion of the image portion) X are stored in advance, and a feature image is detected in accordance with the detection algorithm. A template setting algorithm for setting a rectangular local area including a neighborhood area of the obtained feature image X as a template T is stored in advance, and the template T is automatically set according to the setting algorithm.

As described above, the detection of the characteristic image X and the setting of the template T are not limited to those performed automatically, and the operator observes the radiation image P2 displayed on a display device such as a CRT or the like. A feature image X is searched for in the overlapping area of the displayed radiation image P2, and a template T is manually set via an interface such as a touch panel, a mouse, and a touch panel so as to surround the obtained feature image. Is also good.

As the characteristic image X, for example, when an alignment marker formed of a material having an extremely low radiation transmittance is arranged in advance in an overlapping portion of the two sheets 31 and 32 and photographing and recording are performed. , Both radiation images P1,
The image of this marker that appears in each overlapping area of P2 can also be applied.

The connection processing means 15 includes the positioning means 14
The data S2 of the second radiographic image P2 is adopted as the image data of the overlapping portion of the two radiographic images P1 and P2 aligned according to the above, and the image data S1 of the other non-overlapping portion is used. , S2, respectively, to perform a concatenation process on both image data S1, S2.

Next, the operation of the radiation image processing apparatus according to this embodiment will be described.

First, as shown in FIG. 2, the radiation images P of the subject are recorded on the two stimulable phosphor sheets 31 and 32 from the two sheets 31 and 32, respectively. Two pieces of radiation image data S1 and S2 respectively representing the two obtained radiation images P1 and P2 are input to the overlapping area detection means 11.

Based on the first radiation image data S1, the overlapping area detecting means 11 converts the boundary line image 1c of the overlapping portion with the second sheet 32, which appears in the first radiation image P1, by the above-described operation. The range of the distance L from the boundary image 1c to the overlapping area side edge (lower edge) 1b of the first radiation image P1 is detected as the overlapping area (FIGS. 3A and 3B). On the other hand, the range of the distance L from the overlapping area side edge (upper edge) 2a of the second radiation image P2 to the overlapping area side edge 1b of the first radiation image P1 is defined as the overlapping area (FIG. 3 (2)).

When the overlapping area in each of the radiation images P1 and P2 is detected in this manner, the template setting means 12 next determines the overlapping area of the second radiation image P2 according to a feature image detection algorithm stored in advance. A feature image X recorded in the area is automatically detected, and a rectangular local area including a neighborhood area of the detected feature image X is automatically set as a template T according to a template setting algorithm stored in advance. Set (Fig. 3
(2)).

Next, the template matching means 13
Is within the overlapping area of the first radiation image P1,
A search is made for an area T ′ that matches the template T set in the overlapping area of the radiation image P2 of
Is the area T ′ of the detected first radiation image P1 and the second area
The first radiation image P1 and the second radiation image P2 are aligned so that the template T of the radiation image P2 of the second radiation image P2 is matched. At the time of this alignment, at least one of the two images is rotated as necessary to match the region T 'with the template T. However, the first radiation image P detected when the overlapping area is detected by the overlapping area detecting means 11 described above.
1 has an inclination with respect to the horizontal direction (the direction in which the upper edge or the lower edge of the radiation image P1 extends), the upper edge 2a of the second radiation image P2 in advance.
Is rotated by the template setting means 12 with respect to the first radiation image P1 so that the template T becomes parallel to the boundary image 1c.
May be set.

The data S1 and S2 of the two radiation images P1 and P2 thus aligned by the alignment unit 14 are combined by the connection processing unit 15 into the data shown in FIG.
The data S is connected to the data S of the two radiation images P, reconstructed, and output to an external filing device or the like. In this connection processing, the connection processing means 15 adopts the data S2 of the second radiation image P2 as the image data of the overlapping portion of the two radiation images P1 and P2, and performs another overlapping operation. The image data S1 and S
2 and the image data S1 and S2 are connected.

As described above, according to the radiation image processing apparatus of the present embodiment, the feature recorded in the overlapping area corresponding to the overlapping portion of the second radiation image P2 with the first stimulable phosphor sheet 31. An area including the image X is set as a template T, and in an overlapping area corresponding to the overlapping part of the first radiation image P1 with the second stimulable phosphor sheet 32, an area T 'that matches this template T Are searched, and the first radiation image P1 and the second radiation image P2 are aligned so that the region T 'obtained by the search matches the template T. P2
Unlike the case where are connected without gaps, the positioning can be performed with high accuracy, and as a result, the normal radiation image P can be reconstructed.

Further, since the template matching is performed in a limited area only in the overlapping area, the time required for the template matching process can be shortened. Further, since the template matching is performed in such a narrow area, the accuracy of the template matching can be reduced. Can be enhanced.

In the radiation image processing apparatus according to the present embodiment, a description has been given by taking as an example a radiation image in which the boundary image 1c is not inclined with respect to the horizontal direction.
It is needless to say that the present invention can be applied to a radiation image inclined with respect to the horizontal direction without any problem.

In the radiation image processing apparatus according to the present embodiment, one template is set.
In order to further improve the accuracy of the positioning of one radiation image, it is preferable to set two or more templates in the overlapping area, and it is desirable to adopt an embodiment having such a configuration.

In the radiation image processing apparatus of this embodiment, the presence of the boundary image 1c in the first radiation image P1, that is, the first stimulable phosphor sheet 31
It is assumed that the stimulable phosphor sheet 31 or 32 is located farther away from the subject than the stimulable phosphor sheet 32.
However, if it is not known whether the second radiation image P1 is located farther from the subject than the other radiation image 32 or 31, the boundary image does not necessarily exist in the first radiation image P1.
2 in some cases.

Therefore, in such a case, the evaluation value M is calculated by the above equation (1) for both the radiation images P1 and P2 by utilizing the detection operation of the boundary image by the overlapping area detection means 11 described above. And any radiation image P
Whether or not a boundary image exists at 1 or P2 may be specified.

That is, the overlapping area detecting means 11 obtains the above-mentioned evaluation value M for each line for both the input image data S1 and S2, and of the evaluation value M for each line, the absolute value of the evaluation value M is the largest. This is set as each evaluation value | M | max for each of the radiation image data sets S1 and S2. Here, the overlapping area detecting means 11 compares the respective evaluation values | M | max of both the radiation image data S1 and S2, and specifies that the boundary line image exists in the larger one of the evaluation values | M | max. I do.

That is, on the side where the boundary image exists, the entire area on the horizontal line (X direction in FIG. 4) where the boundary image exists between the fourth pixel and the fifth pixel of the filter f is Since the evaluation value M is deviated in one direction of positive (+1) or negative (-1), the absolute value | M | of the evaluation value M of the total sum of one line is determined on the side where no boundary image exists. This is an extremely large value as compared with. On the side where the boundary image does not exist, there is no image portion in which the evaluation value M is shifted in one direction in the positive or negative direction over the entire area on one line, and positive, negative or 0 occurs randomly. This is because the absolute value | M | of the evaluation value M of the sum of the entire one line is relatively small as compared with the case where the boundary image exists.

The radiation image P1 or P2 on the side identified by the overlapping area detecting means 11 as having a boundary image exists.
, A boundary line image is detected based on the above-described evaluation value M. The case where the boundary line image exists in the first radiation image P1 and the case where the boundary line image exists in the second radiation image P2 It should be noted that the sign of the evaluation value M is reversed. That is, in FIG. 2, the lower sheet 32 is
In the case where the overlap is made farther from the subject than the upper sheet 31, a boundary image is formed on the upper part of the radiation image P2 obtained by reading from the lower sheet 32,
In this case, according to the above equation (1), in the line where the evaluation value M is negative and the absolute value is the maximum, the fourth pixel k
It can be detected that a boundary image exists between the second pixel and the fifth pixel k3.

As described above, the detection processing of the boundary line image is performed on the two radiation image data sets S1 and S2 representing the two radiation images P1 and P2, and based on the result, which stimulable phosphor sheet 31 or 32 is determined. However, it is useful to automate the connection processing of the radiation images by specifying whether or not the imaging recording arranged on the far side from the subject has been performed.

A radiation image reading device (not shown) for reading the radiation image data S1 and S2 from the stimulable phosphor sheets 31 and 32,
When reading images S1 and S2, it is impossible to completely read the image recorded on the edge of each sheet. For example, if the image P2 recorded on the sheet 32 is as shown in FIG. From the edge 2a of the image P2 obtained by reading, the image information in the area of the length m which cannot be read is lost, and the image P by the length m from the edge 2a is lost.
An image P2 in which the position 2a 'eroded on the second side is the edge 2a
(FIG. 6 (2)) is input to the overlapping area detecting means 11.

In this case, the template matching means 1
3, the radiation image P1 and the radiation image P2 are aligned by the alignment means 14, and the connection processing means 15 performs the connection processing and reconstructs. In the area part lost in the above (area part of length m), the second
Since there is no radiation image data S2 of the first radiation image data, the connection processing means 15 determines that the first radiation image corresponding to the image portion of the length m from the boundary image 1c of the first radiation image P1 for the region of the length m Radiation image P using image data S1
Is reconstructed (FIG. 7).

At this time, for a band-shaped area having a length m from the boundary image 1c reconstructed by employing the first radiation image data S1, an image portion (a part of the second sheet 32 overlapped and recorded) Since the image data is the image data of the first radiation image P1), the density is lower than other portions. Therefore, if the link processing means 15 performs a correction process such as uniformly shifting the density of this band-shaped region employing the first radiation image data S1 so as to substantially match the density of the other portions. Good.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an embodiment of a radiation image processing apparatus that performs a radiation image connection processing method of the present invention.

FIG. 2 is a diagram showing a state in which one radiation image of a subject is recorded on two stimulable phosphor sheets partially overlapping each other;

FIG. 3 is a view showing two radiographic images respectively read from the two stimulable phosphor sheets shown in FIG. 2;

FIG. 4 is a diagram illustrating an operation of boundary image detection.

FIG. 5 is a diagram showing a radiation image subjected to a connection process by the radiation image processing apparatus shown in FIG. 1;

FIG. 6 is a view for explaining that a part of an overlapping area is missing when reading an image;

FIG. 7 is a diagram showing a radiographic image subjected to a linking process based on a radiographic image in which a part of an overlapping area is missing;

[Explanation of symbols]

 11 overlapping area detecting means 12 template setting means 13 template matching means 14 positioning means 15 connection processing means 31 first stimulable phosphor sheet 1a boundary image shown in first radiation image 1b lower end of first radiation image Edge 32 Second stimulable phosphor sheet 32a Edge of overlapping portion side of second stimulable phosphor sheet 2a Edge of second radiation image P1 First radiation image P2 Second radiation image P Original radiation Image and Reconstructed Radiation Image S1 First Radiation Image Data S2 Second Radiation Image Data S Reconstructed Radiation Image Data

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G06F 15/66 470J F term (Reference) 2G001 AA01 BA11 CA01 DA02 DA06 DA09 FA06 HA07 HA13 HA15 JA13 JA20 LA01 2G083 AA03 BB05 CC10 DD20 EE10 2H013 AC03 AC11 4C093 AA16 AA26 CA50 DA03 EA02 EA05 EB05 EE01 FD04 FD05 FD20 FF15 FF16 FF19 FF27 FF35 FF37 FG05 5B057 AA08 BA03 CB08 CC03 CE10 DA07 DB09 DC16 DC22

Claims (14)

[Claims] 1. A radiographic image of a subject is recorded over a plurality of stimulable phosphor sheets in which a part of two adjacent stimulable phosphor sheets are overlapped with each other. When connecting a plurality of radiation images obtained by reading from each of a plurality of stimulable phosphor sheets individually so as to reconstruct the one radiation image, the two adjacent stimulable phosphors are used. A radiation image obtained by reading from any one of the stimulable phosphor sheets of the sheet, at least one or more regions in an overlapping region corresponding to an overlapping portion with the other stimulable phosphor sheet, as a template Setting, in the overlapping area corresponding to the overlapping portion of the one stimulable phosphor sheet of the radiation image obtained by reading from the other stimulable phosphor sheet, Searches for a region that matches the over preparative, so as to coincide with said and the search to the area obtained template connection processing method of radiation images, wherein the aligning of the two radiation images. 2. A first radiographic image obtained by reading from a first stimulable phosphor sheet farther from the subject among the two stimulable phosphor sheets, the second radiographic image being closer to the subject. A boundary image of an overlapping portion with the stimulable phosphor sheet of No. 2 is detected, and based on the detected boundary image,
The method according to claim 1, wherein the overlapping area is detected. 3. The connection of radiation images according to claim 2, wherein the detection of the boundary image is performed by performing an edge detection process on radiation image data representing the first radiation image. Processing method. 4. The method according to claim 1, wherein an area including a characteristic image in an overlapping area of the radiation images is set as the template. 5. The feature image is automatically detected based on an image in the overlapping area in the radiation image,
The method according to claim 4, wherein the template is automatically set based on the detected characteristic image. 6. The method according to claim 6, wherein, for the overlapping area, a second radiation image obtained by reading from a second stimulable phosphor sheet of the two stimulable phosphor sheets closer to the subject is used as the second radiation image. Overwriting the first radiation image obtained by reading from the first stimulable phosphor sheet on the far side from the subject, and connecting the first radiation image and the second radiation image. The radiographic image connection processing method according to any one of claims 1 to 5, wherein 7. An edge detection process is performed on two pieces of radiation image data representing the two radiation images, and based on a result of the edge detection process, which one of the two radiation images is farther from the subject. The first radiation image read from the first stimulable phosphor sheet or the second radiation image read from the second stimulable phosphor sheet near the subject. 7. One of claims 1 to 6, characterized in that:
13. The method for linking radiographic images according to the above section. 8. A radiation image of a subject is recorded over a plurality of stimulable phosphor sheets in which a part of two adjacent stimulable phosphor sheets are overlapped with each other so as to overlap with each other. A radiation image processing apparatus comprising: a plurality of radiation images separately read from each of the stimulable phosphor sheets; and a coupling processing unit configured to perform a coupling process so as to reconstruct a radiation image of the subject. At least one of the radiation images obtained by reading from one of the two stimulable phosphor sheets in the overlapping area corresponding to the overlapping portion with the other stimulable phosphor sheet. Template setting means for setting one or more regions as a template; and the one storage property of the radiation image obtained by reading from the other storage phosphor sheet. A template matching unit that searches for an area that matches the template in an overlapping area corresponding to an overlapping part of the light body sheet; and the two sets that match the area obtained by the search with the template. A radiation image processing apparatus comprising: a positioning unit that performs positioning of a radiation image. 9. A first radiographic image obtained by reading from a first stimulable phosphor sheet farther from the subject among the two stimulable phosphor sheets, a first radiographic image closer to the subject. A boundary image of an overlapping portion with the stimulable phosphor sheet of No. 2 is detected, and based on the detected boundary image,
9. The radiation image processing apparatus according to claim 8, further comprising an overlap area detection unit that detects the overlap area. 10. The apparatus according to claim 1, wherein the overlapping area detecting means detects the boundary image by performing edge detection processing on the radiation image data representing the first radiation image. The radiation image processing apparatus according to claim 9. 11. The apparatus according to claim 8, wherein the template setting unit sets an area including a feature image in the overlapping area as the template. Radiation image processing device. 12. The apparatus according to claim 8, wherein the template setting means automatically detects the feature image and automatically sets the template based on the detected feature image. 12. The radiation image processing apparatus according to any one of items 1 to 11. 13. The connection processing means according to claim 2, wherein said overlapping area is obtained by reading a second stimulable phosphor sheet of said two stimulable phosphor sheets closer to said subject out of said two stimulable phosphor sheets. A first radiation image obtained by reading a radiation image from the first stimulable phosphor sheet on the far side from the subject;
The radiation image according to any one of claims 8 to 12, wherein the first radiation image and the second radiation image are connected to each other by overwriting the radiation image. Processing equipment. 14. An edge detection process is applied to two radiation image data representing two radiation images obtained by reading from the two stimulable phosphor sheets, respectively.
Based on the result of the edge detection processing, which of the two radiation images is closer to the first radiation image or the first radiation image obtained by reading from the first stimulable phosphor sheet farther from the subject. 14. A radiographic image specifying means for specifying whether or not the radiographic image is a second radiographic image obtained by reading from the first stimulable phosphor sheet on the side. A radiation image processing apparatus according to the item.