JP2955876B2 - Breast image recording position recognition device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to recording on substantially the entire surface of a recording sheet obtained by reading substantially the entire surface of a recording sheet on which a radiation image of a breast is recorded in a partial area. The present invention relates to a breast image recording position recognition device that recognizes a position where a radiation image of a breast is recorded on a recording sheet, based on an image signal carrying the entire radiation image.

2. Description of the Related Art In various fields, reading a recorded radiation image to obtain an image signal, performing appropriate image processing on the image signal, and reproducing and recording the image have been performed in various fields. For example,
An X-ray image is recorded using an X-ray film having a low gamma value designed to be compatible with the subsequent image processing, and the X-ray image is read from the film on which the X-ray image is recorded and converted into an electric signal. By subjecting the electric signal (image signal) to image processing and reproducing it as a visible image in a copy photograph or the like, a system capable of obtaining a reproduced image with good image quality performance such as contrast, sharpness, and graininess is provided. It has been developed (see JP-B-61-5193).

In addition, the applicant (X-ray, α-ray, β-ray,
Irradiation with gamma rays, electron beams, ultraviolet rays, etc. accumulates a part of this radiation energy, and then irradiation with excitation light, such as visible light, causes a stimulable phosphor (luminous) to emit stimulated emission according to the accumulated energy. Using a photostimulable phosphor), a radiation image of a subject such as a human body is once photographed and recorded on a sheet-shaped stimulable phosphor, and the stimulable phosphor sheet is scanned with excitation light such as a laser beam to radiate. Generates emitted light, obtains an image signal by photoelectrically reading the obtained stimulated emission light, and outputs a radiation image of the subject as a visible image to a recording material such as a photographic photosensitive material or a CRT based on the image signal. There has already been proposed a radiation image recording / reproducing system (Japanese Patent Laid-Open No. 55-12429).
Nos. 56-11395, 55-163472, 56-104645
No. 55-116340, etc.).

This system has a practical advantage that an image can be recorded over an extremely wide radiation exposure area as compared with a conventional radiographic system using silver halide photography. That is, in the case of the stimulable phosphor, it has been recognized that the amount of emitted light that is stimulated by excitation after accumulation is proportional to the radiation exposure amount over an extremely wide range. Even if fluctuates considerably, the amount of the stimulating light emitted from the stimulable phosphor sheet is read by the photoelectric conversion means with the reading gain set to an appropriate value and converted into an electric signal. By outputting a radiation image as a visible image on a recording material such as a photographic light-sensitive material or a display device such as a CRT using, a radiation image which is not affected by a change in radiation exposure can be obtained.

In the above-described system, before obtaining an image signal by reading under optimal reading conditions according to the dose of radiation applied to the stimulable phosphor sheet, the stimulable phosphor sheet is scanned with a low-level light beam in advance. A pre-read for reading the outline of the radiation image recorded on this sheet is performed, a pre-read image signal obtained by this pre-read is analyzed, and then the sheet is irradiated with a light beam having a higher level than the light beam at the time of the pre-read. There is also a system which is configured to perform a main reading in which an image signal is obtained by reading the radiation image under the optimum reading conditions (see Japanese Patent Application Laid-Open Nos. 58-67240 and 58-6).
Nos. 7241 and 58-67242).

The reading condition is a general term for various conditions that affect the relationship between the amount of stimulated emission light in reading and the output of the reading device. For example, a reading gain, a scale factor, or a scale factor that determines an input / output relationship. , And the power of the excitation light in reading.

Further, the high level / low level of the light beam means that the intensity of the light beam applied per unit area of the sheet is large / small, or the intensity of the stimulating light emitted from the sheet is the light beam. (Having a wavelength sensitivity distribution) means the magnitude of the weighted intensity after weighting the intensity of the light beam applied to the unit area of the sheet by the wavelength sensitivity. Methods for changing the beam level include using a light beam of a different wavelength, changing the intensity of the light beam emitted from a laser light source, etc., and inserting or removing an ND filter or the like in the optical path of the light beam. Various known methods such as a method of changing the beam intensity, a method of changing the scanning density by changing the beam diameter of the light beam, and a method of changing the scanning speed can be used.

In addition, regardless of whether the system performs the pre-reading or the system which does not perform the pre-reading, the obtained image signal (including the pre-reading image signal) is analyzed, and an optimum image processing condition when performing image processing on the image signal is determined. Some systems let you decide. Here, the image processing condition is a general term for various conditions when a process that affects the gradation and sensitivity of a reproduced image based on an image signal is performed on the image signal. The method for determining the optimum image processing conditions based on this image signal is not limited to the system using the stimulable phosphor sheet, but obtains the image signal from a radiation image recorded on a recording sheet such as a conventional X-ray film. It is also applied to the system.

When taking a radiographic image on a recording sheet,
To prevent radiation from irradiating parts that are not necessary for observation of the subject, or to irradiate radiation to parts that are not necessary for observation, scattered radiation enters the parts necessary for observation from that part, degrading image quality performance. In many cases, imaging is performed using an irradiation field diaphragm that limits the irradiation area of radiation so that only a necessary part of the subject and a part of the recording sheet (in the irradiation field) are irradiated. Also, even in the irradiation field,
In addition to the subject portion in which the subject is photographed and recorded, there is often a direct radiation portion directly irradiated with radiation that does not pass through the subject. Of these areas, only the subject portion is required to obtain a reproduced image. Therefore, the subject portion in the radiation image recorded on the entire recording sheet is recognized, and an image signal corresponding to the subject portion is recognized. By extracting, a reproduction image with excellent observation suitability can be obtained by obtaining the optimum reading conditions and image processing conditions based on the extracted image signal. In recognizing the subject portion, for example, characteristics appearing on the radiographic image due to the structure of the imaging device that captures the subject, a unique shape of the subject, and the like are often considered. For example, Japanese Patent Application Laid-Open No. 61-170178 discloses an X-ray image of a human breast, in which the breast is photographed in a substantially semicircular shape on a recording sheet, and the X-rays are directly recorded outside a substantially semicircular arc. Utilizing the fact that the direct X-ray part irradiated on the sheet is recorded, the change in the image signal at the boundary between the subject part (shadow of the breast) and the direct X-ray part is detected, so A method for recognizing whether a subject portion exists at a position is described.

(Problems to be Solved by the Invention) However, shadows of the right and left breasts may be recorded on one recording sheet. In this case, when the method described in the above-mentioned Japanese Patent Application Laid-Open No. 61-170178 is used. In addition to the object part, an area outside the irradiation field directly irradiated with only the scattered radiation directly adjacent to the X-ray part may be erroneously recognized as the object part. In this case, correct reading conditions and image processing conditions are required. In some cases, the finally obtained image is an image with poor image quality and poor observation suitability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a breast image recording position recognition device capable of more accurately recognizing a recording position of a shadow (subject portion) of a breast on a recording sheet.

(Means for Solving the Problems) In the first breast image recording position recognition device of the present invention, the radiation transmitted through the breast is applied to the recording sheet, so that the shadow of the breast is shifted from the edge of the recording sheet. One or a plurality of subject parts recorded in a shape protruding in a substantially semicircular shape toward the center of the recording sheet, and the subject is directly irradiated on the recording sheet without the radiation penetrating the subject. A direct radiation portion formed so as to surround a substantially semicircular edge of the portion, and a scattered radiation portion formed adjacent to the direct radiation portion by irradiating the recording sheet with scattered radiation. Based on an image signal carrying a radiographic image, one or more candidates for the subject portion are determined by capturing changes in the image signal at a substantially semicircular edge of the subject portion. Candidate extracting means, and determining whether each candidate is correct based on an average value of each image signal corresponding to the subject portion obtained as the candidate on the radiographic image of the subject portion. And a position recognizing means for recognizing the position.

Here, the “average value” is not limited to an average value by arithmetic mean, but is an average value of image signals such as an average value by geometric mean, median value, (maximum value + minimum value) / 2. Any index can be used.

Further, in the second breast image recording position recognition device of the present invention, the radiation transmitted through the breast is irradiated on the recording sheet, so that the shadow of the breast is substantially directed from the periphery of the recording sheet toward the center of the recording sheet. One or a plurality of subject portions recorded in a shape projecting in a semicircle, and a substantially semicircular edge of the subject portion by directly irradiating the recording sheet without the radiation penetrating the subject. The direct radiation portion formed so as to surround, and by irradiating the recording sheet with scattered radiation, an image signal carrying a radiation image having a scattered radiation portion formed adjacent to the direct radiation portion A candidate axis deriving means for obtaining one or a plurality of candidates for the subject portion by capturing a change in the image signal at a substantially semicircular edge of the subject portion, Position recognition means for recognizing the position of the subject portion on the radiographic image by determining whether each candidate is correct based on the geometric shape of the subject portion obtained as a complement. Is what you do.

(Function) The present invention provides one or a plurality of object portions recorded in a shape protruding in a substantially semicircular shape from the edge of the recording sheet toward the center of the recording sheet, without causing radiation to pass through the object. A direct radiation section formed so as to surround the substantially semicircular edge of the object portion by being directly irradiated on the recording sheet, and a scattered radiation is irradiated on the recording sheet to directly adjoin the radiation section. A radiation image having the formed scattered radiation part is targeted.

The first breast image recording position recognizing device of the present invention pays attention to the fact that the radiation dose is different between the subject part and the scattered radiation part, and recognizes the position of the subject part more correctly. That is, the first breast image recording position recognition device of the present invention is based on an image signal carrying the radiation image,
For example, the change in the image signal at the substantially semicircular edge of the subject portion is captured by using the method described in JP-A-61-170178 described above or the method described in the embodiment described later. After determining one or a plurality of candidates, the correctness of each candidate is determined based on the average value of the image signal corresponding to each of the subject portions determined as the candidates. Can be recognized more accurately.

In addition, it is possible to more correctly recognize the position of the subject portion by focusing on the fact that the subject portion has a substantially semicircular shape. The second breast image recording position recognizing device of the present invention obtains one or more candidates for the subject portion in the same manner as the first breast image recording position recognizing device, and then obtains the subject portion obtained as the candidate. Since the correctness of each candidate is determined based on the geometric shape of the above, the position of the subject portion on the radiographic image can be more accurately recognized as in the first breast image recording position recognition device.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram schematically showing an example of an X-ray imaging apparatus for performing mammography. In this photographing apparatus, the above-described stimulable phosphor sheet is used.

A cassette 2 accommodating a stimulable phosphor sheet is placed on an imaging table 1, and the cassette 2 and a pressing plate 3 made of an acrylic plate or the like sandwich and press the breast 4, which is a subject, and press the pressing plate 3. An X-ray is emitted toward the subject 4 from an X-ray source 5 disposed through a cone cylinder 6 having a semicircular cross section.

FIG. 2 shows an X-ray taken by the X-ray imaging apparatus shown in FIG.
It is a figure showing an example of a line image.

A semi-circular irradiation field 7 exists on the stimulable phosphor sheet 11, and within the irradiation 7, a direct X-ray portion 8 and a direct X-ray portion 8 are provided.
There is a subject portion 9 surrounded by. Outside the semi-circular irradiation field 7 composed of the direct X-ray part 8 and the object part 9, there is a scattered ray part 10 (a dotted part in the figure) in which scattered X-rays are recorded.

Here, along the straight line y of the X-ray image, the amount of energy stored and recorded in the stimulable phosphor sheet 11 (the value of the image signal when reading the stored and recorded image as described later) And corresponding to the density of the visible image reproduced and output based on the image signal),
As shown on the right side of FIG. 2, a curve is obtained in which the energy amount of the direct X-ray part 8 is the largest, the energy amount of the subject part 9 is the next largest, and the outside of the irradiation field 7 is the smallest.

FIG. 3 is a perspective view showing an example of an X-ray image reading device including an example of the breast image recording position recognition device of the present invention. This example is a system for pre-reading using a stimulable phosphor sheet.

The stimulable phosphor sheet 11 on which the X-ray image including the breast is recorded in the imaging apparatus (see FIG. 1) is scanned with a weak light beam first, and only a part of the X-ray energy stored in the sheet 11 is scanned. It is set at a predetermined position of the pre-reading means 100 which performs pre-reading by releasing. The stimulable phosphor sheet 11 set at this predetermined position is conveyed (sub-scanning) in the direction of arrow Y by sheet conveying means 13 such as an endless belt driven by a motor 12. On the other hand, the weak light beam 15 emitted from the laser light source 14 is reflected and deflected by the rotating polygon mirror 16 rotating at high speed in the direction of the arrow driven by the motor 23, and after passing through the focusing lens 17 such as an fθ lens, the mirror 18 The light is incident on the sheet 11 by changing the optical path, and the main scanning is performed in the arrow X direction substantially perpendicular to the sub-scanning direction (arrow Y direction). From the portion of the stimulable phosphor sheet 11 irradiated with the light beam 15, a stimulable luminescent light 19 of an amount corresponding to the accumulated and recorded X-ray image information is diverged.
Is guided by a light guide 20 and is photoelectrically detected by a photomultiplier (photomultiplier tube) 21. The light guide 20 is formed by molding a light-guiding material such as an acrylic plate, and is arranged such that a linear incident end face 20a extends along a main scanning line on the stimulable phosphor sheet 11. The light receiving surface of the photomultiplier 21 is connected to the emission end face 20b formed in an annular shape. Above end face
The stimulated emission light 19 that has entered the light guide 20 from the light guide 20a travels through the inside of the light guide 20 by repeating total internal reflection, and the emission end face
Emitted from 20b and received by the photomultiplier 21,
The photomultiplier 21 converts the amount of stimulated emission light 19 representing an X-ray image into an electric signal.

The analog output signal S output from the photomultiplier 21 is logarithmically amplified by a logarithmic amplifier 26, and the A / D converter 2
7 is digitized, the preliminary read-out image signal S _P is obtained. Pre-reading the image signals S _P has a value proportional to the logarithm of the amount of the emitted light 19.

In the pre-reading, reading conditions such as a voltage value applied to the photomultiplier 21 and an amplification factor of the logarithmic amplifier 26 are set so that reading can be performed over a wide area of the X-ray energy stored in the stimulable phosphor sheet 11. Stipulated.

Pre-reading the image signals S _P obtained is input to the storage unit 28, and is temporarily stored. Thereafter, the preliminary read-out image signals S _P stored in the storage unit 28 is input to the arithmetic unit 29 is read out, the arithmetic unit 29, based on the inputted pre-reading image signals S _P, the stimulable phosphor sheet The subject portion in the X-ray image formed on 11 is recognized. When the subject unit is recognized, the amplification factor of the pre-reading image signals corresponding to the object portion on the basis of the S _P read during real reading conditions G _1, for example, 'voltage and a logarithmic amplifier 26 to be applied to' the photomultiplier 21 Etc. are required.

The stimulable phosphor sheet 11 'for which pre-reading has been completed is set at a predetermined position of the main reading means 100', and the sheet 11 'is scanned by a light beam 15' which is stronger than the light beam used for pre-reading, as described above. image signals under the condition G ₁ read defined Te is obtained, the configuration of this reader in stage 100 'for the configuration substantially the same as the destination reader in stage 100, corresponding to the components of the previous reader in stage 100 configured Elements are indicated by adding dashes to the numbers used in the look-ahead means 100, and descriptions thereof are omitted.

Image signals S _Q obtained by being digitized by A / D converter 27 'is sent to the image processing unit 50. Appropriate image processing is performed on the image processing unit 50 in the image signal S _Q.
The image signal subjected to the image processing is sent to the reproducing device 60, and an X-ray image based on the image signal is reproduced and displayed.

Next, a method for recognizing an object part on the basis of the preliminary read-out image signals S _P by the operation means 29.

4A to 4C are diagrams showing examples of X-ray images including a breast. Parts corresponding to the X-ray image shown in FIG. 2 described above are given the same numbers as in FIG.

FIG. 4A shows an X-ray image in which only one of the left and right breasts is recorded on the sheet 11, and FIGS. 4B and 4C show X-ray images in which the left and right breasts are recorded above and below the sheet 11. Is represented. Here, in the X-ray image shown in FIG. 4B, two direct X-ray portions 8 formed so as to surround two substantially semicircular subject portions 9 are connected to each other. In the X-ray image shown in FIG. 4C, of the two upper and lower direct X-ray parts 8, the upper direct X-ray part 8 in the figure is formed slightly shifted to the right in the figure.

As shown in FIGS. 4A to 4C, only one of the right and left breasts may be photographed and recorded on the stimulable phosphor sheet 11, and the stimulable phosphor sheet 11 has two opposing breasts. From the sides (here, the upper and lower sides), the stimulable phosphor sheet 11
The left and right breasts may be recorded so as to project in a substantially semicircular shape toward the center of the breast. In addition, as shown in FIG. 4C, the X-ray part 8 may be recorded with a slight deviation from the standard position, and although not shown here, the subject part 9 may be recorded with a slight deviation. .

Here pre-reading image signals carrying the direct X-ray unit 8 S _P, since it has a large value as shown in FIG. 2, the predetermined threshold indicating the preliminary read-out image signals S _P in FIG. 2 By binarizing with the value Th, 1 is directly assigned to the signal representing the X-ray portion 8 and 0 is assigned to the signal representing the other region, and a binary signal is obtained.

Next, based on this binary signal, each side 11a, 11b, 11c, 11d of a binarized X-ray image (hereinafter, referred to as an X-ray image without distinction whether or not binarized). A point where the binary signal is “1” is searched from each of the middle points Ca, Cb, Cc, and Cd (see FIGS. 4A to 4C) toward the opposing sides. For example, 4A
In the search starting from the middle point Ca of the lower side 11a of the figure, the point A is obtained as the point where the binary signal becomes '1'.
In this way, before reaching the opposite side, the binary signal is '1'
Is found, then return by the distance d from that point, and then search in parallel with each of the sides 11a, 11b, 11c, 11d where the midpoints Ca, Cb, Cc, Cd, which are the starting points, are located And the binary signal is '1'
(The points B and C in the search starting from the middle point Ca in FIG. 4A) are obtained. When three points (points A, B, and C) at which the binary signal is “1” are obtained in this manner, it is recognized that the subject portion 9 exists on the corresponding side. After that, it is determined whether or not the subject part 9 obtained as described above is a true subject part 9. Candidates ”.

In the X-ray image shown in FIG. 4A, only one candidate for the object portion 9 is obtained on the side 11a side, and in the X-ray image shown in FIG. 4B, the object portion 9 is obtained for all four sides 11a, 11b, 11c, and 11d. Are obtained, and for the X-ray image shown in FIG.
It is recognized that there are candidates for the subject portion 9 at positions corresponding to the two sides 11a, 11b, 11c. In the present embodiment, the function of the calculating means 29 shown in FIG. 3 for obtaining the candidates is considered as an example of the candidate extracting means according to the present invention.

FIG. 5 is a diagram schematically showing the arrangement position on the sheet 11 of the candidate for the subject portion 9 obtained as described above. In the figure, □ indicates a sheet (entire X-ray image), and ○ indicates the position of the candidate.

As shown in the group of FIG. 5 (a), when only one candidate of the subject portion 9 is obtained on the sheet 11, it is determined that the candidate is the correct subject portion without any doubt.

When two candidates are present along the FIG. 5 (b) two sides adjacent to each other as shown in the group, the average value of the preliminary read-out image signals S _P output respective candidate areas for each candidate It is determined that the one with the higher average value is the true subject portion 9.

When two candidates are present along two opposing sides, as shown in the group of FIG. 5 (c) is an average value for each candidate of the pre-reading image signals S _P, these mean values Have substantially the same value, it is determined that the left and right breasts are recorded X-ray images, that is, both candidates are true subject parts 9, and their average values are significantly different from each other. In this case, it is determined that the larger value is the true subject portion 9.

Also, when the FIG. 5 (d) are shown as three candidates obtained the first mean value of the preliminary read-out image signals S _P corresponding to two candidates determined along the opposing sides When obtains a second mean value of the preliminary read-out image signals S _P corresponding to the remaining one candidate, the larger of these two average values are adopted. That is, when the first average value is larger, it is determined that the two candidates obtained along the sides facing each other are the true subject portions 9, and the second average value is larger. In this case, it is determined that only one remaining candidate is the true subject portion 9. When the first average value is larger, the two candidates obtained along the sides opposite to each other as described above are not immediately determined to be the true subject portion 9 but the above-described second average value is used. 5 As in the case of the group of FIG. 5 (c), the average value of each of these two candidates is obtained, and when these two average values have almost the same value, both of these two candidates are true. It is also possible to judge that the subject portion 9 is a true subject portion 9 when the two average values are significantly different from each other.

Further, when four candidates are obtained as shown in FIG. 5 (e), each of the two sets obtained by combining the two candidates obtained along the opposing sides is referred to as a first candidate in the candidate area. the average value of the read image signals S _P, the larger of two candidates of these two averages is determined to be true object portion 9. Also in this case, instead of immediately determining that the two candidates having the larger average value are the true subject portions 9, the average value is further obtained for each of the two candidates having the larger average value. If the two averages have substantially the same value, it is determined that both of these two candidates are true subject parts 9, and if the two averages are significantly different from each other, the value is determined. May be determined to be the true subject portion 9.

In this embodiment, the calculating means 29 shown in FIG.
Of, as described above the average value of the preliminary read-out image signals S _P output each candidate region, functions that each candidate based on the average value to determine whether it is a true object portion, the present invention Of the first breast image recording position recognition device.

As described above, after once recognizing an object portion by capturing a change in the preliminary read-out image signals S _P of a substantially semi-circular edge of the object 9, the subject unit is whether the true subject portion Since the determination is made, the true position of the subject portion is accurately obtained.

Once the method the subject part after recognizing the object unit determines whether the real object portion is not limited to the determination method based on the average value of the preliminary read-out image signals S _P, as described above, the subject 9 May be determined based on the geometrical shape of the subject portion that is substantially semicircular.

FIG. 6 is a view showing an X-ray image similar to FIG. 4B for explaining an example of the determination method based on this geometrical shape. For this X-ray image, four candidates are obtained as shown in FIG. 5 (e). Here, the candidates obtained along the side 11a and the candidates obtained along the side 11d will be described.

After the four candidates are determined as described above, the point closest to the center of the sheet 11 is determined for each candidate. That is, for example, a point D is obtained for a candidate obtained along the side 11a, and a point E is obtained for a candidate obtained along the side 11d. In addition, one of two points in contact with the corresponding side is obtained for each candidate. That is, for example, a point F is obtained for a candidate obtained along the side 11a, and a point G is obtained for a candidate obtained along the side 11d.

When two points are obtained for each candidate as described above, it is determined whether the binary signal corresponding to each pixel on the line segment connecting the two points is mainly '0' or mainly '1', When the binary signal is mainly “0”, it is determined that the candidate is the true subject portion 9. That is, regarding the candidate along the side 11a, the binary signal on the line segment connecting the point D and the point F is “0”, so that the candidate along the side 11a is determined to be the true subject part 9, and As for the candidate along 11d, the binary image on the line segment connecting point E and point G is '1', so it is determined that the candidate along side 11d is not true subject portion 9. As described above, the position of the subject portion 9 can be more accurately recognized by extracting the true subject portion 9 from the candidates of the subject portion 9 based on the geometrical shape that the subject portion 9 is substantially semicircular. Can be.

Note that the determination based on the geometric shape that the subject portion 9 is substantially semicircular is not limited to the above-described method. For example, after finding the point closest to the center of the sheet 11 for each candidate, A semicircle passing through the point closest to the center with respect to each midpoint Ca, Cb, Cc, Cd of each side 11a, 11b, 11c, 11d corresponding to the candidate (for example, the candidate corresponding to the side 11a in FIG. 7A) By drawing a semicircular arc J for the candidate corresponding to the side 11d, and calculating the appearance ratio of '0' and '1' of the binary image corresponding to the area within the semicircle. It may be determined whether or not the candidate is the true subject portion 9 or any other method based on a geometric shape.

In the above embodiment, the function of the arithmetic means 29 shown in FIG. 3 for recognizing the true subject portion 9 based on the above-mentioned geometric shape is the same as the position of the second breast image recording position recognition device of the present invention. It is thought of as an example of recognition means.

The calculation for obtaining the candidate of the subject section 9 is not limited to the calculation method described above.

7A and 7B are diagrams showing an X-ray image similar to FIG. 4A for explaining another method for obtaining a candidate for the subject portion 9. FIG.

FIG.7A shows that 45 °, 90 ° from the midpoint Ca of the side 11a to the side 11a.
This indicates that the contour is obtained by searching in the direction of {, 135}. A candidate for the subject portion 9 may be obtained by performing such an operation on each of the sides 11a, 11b, 11c, 11d.

FIG. 7B shows that the contour point of the object portion 9 is obtained from the midpoint Ca of the side 11a in the same manner as the calculation method shown in the above-described embodiment, and two points Ca near both ends sandwiching the midpoint Ca. ′, C
Similarly, a contour point of the object portion 9 is obtained from “a”. In this case, a maximum of nine contour points are obtained, but when only eight or less contour points are obtained, a predetermined predetermined point is determined. It is determined whether or not the subject portion 9 exists based on the algorithm of (1).

It should be noted that the calculation method may be other than the above-described calculation methods, and the candidate extraction means of the present invention may be any calculation method that captures a change in an image signal in the side line of the subject portion, and is limited to a specific calculation method. It is not something to be done. Further, in the embodiment described above to determine the binary signal by binarizing the pre-reading image signals S _P, of the original without generating a binary signal Upon determining a candidate of the object portion preliminary readout image signal S _P It is a matter of course that the candidate of the subject portion may be obtained based on.

Thus the position of the subject portion in the correctly recognized, on the basis of the preliminary read-out image signals S _P corresponding to the subject portion, the reading condition G ₁ during the reading is obtained.

Note that while description has been made by the operation unit 29 for apparatus for determining the reading condition during the real reading, during real reading is a reading at a predetermined reading condition regardless preliminary readout image signal S _P,
The arithmetic unit 29, on the basis of the preliminary read-out image signals S _P, determine the image processing conditions G ₂ when performing image processing on the image signal S _Q in the image processing unit 50, the calculating means as shown by the broken line in FIG. 3 29
In may be the image processing conditions G ₂ obtained as input to the image processing unit 50, or may be calculated both the reading condition and image processing condition by the operation means 29.

In the reading apparatus shown in FIG. 3, the pre-reading means 100 and the main reading means 100 'are separately configured, but as described above, the configurations of the pre-reading means 100 and the main reading means 100' are substantially the same. Therefore, the pre-reading means 100 and the main reading means 100 'may be integrally used. In this case, after pre-reading, the stimulable phosphor sheet 11 may be backed once and then scanned again to perform main reading.

When the pre-reading means and the main reading means are used together, it is necessary to switch the intensity of the light beam between the case of pre-reading and the case of main reading. As described above, as a method of this switching, the light from the laser light source is used. Various methods such as a method of switching the intensity itself can be used.

Further, in the above-described embodiment, the radiation image reading apparatus that performs pre-reading has been described. However, the present invention can be applied to an X-ray image reading apparatus that performs reading corresponding to the above-mentioned main reading without performing pre-reading. In this case, at the time of reading, an image signal is obtained by reading under predetermined reading conditions, and based on this image signal, an image processing condition is obtained by the arithmetic means. It is taken into account when performing processing.

Although the above embodiment deals with an X-ray image of the breast stored and recorded on the stimulable phosphor sheet, the present invention is not limited to the use of the stimulable phosphor sheet. The present invention can be applied to a system using a salt film or the like.

(Effects of the Invention) As described above in detail, the first and second breast image recording position recognition devices of the present invention obtain a candidate for a subject portion by capturing a change in an image signal on a side line of the subject portion. After that, it is determined whether or not the candidate is a subject based on the average value of the image signal in each candidate region obtained for each candidate or the geometric shape of the subject. Therefore, the position of the subject portion can be correctly recognized.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of an example of an X-ray imaging apparatus for performing mammography, FIG. 2 is a diagram showing an example of an X-ray image taken by the X-ray imaging apparatus shown in FIG. FIG. 3 is a perspective view of an example of an X-ray image reading device including an example of a breast image recording position recognition device of the present invention. FIGS. 4A to 4C are diagrams showing examples of an X-ray image including a breast. FIG. 5 is a diagram schematically showing the arrangement positions of the candidates for the subject portion 9 on the sheet, and FIG.
FIGS. 7A and 7B are diagrams showing an X-ray image similar to FIG. 4B to explain an example of a method of determining whether or not the image is based on a geometric shape. FIG. 4B is a diagram showing an X-ray image similar to FIG. 4A for explaining another method for obtaining candidates. DESCRIPTION OF SYMBOLS 1 ... Imaging stand 2 ... Cassette containing stimulable phosphor sheet 3 ... Holding plate 4 ... Breast 5 ... X-ray source 6 ... Cone cylinder 7 ... Irradiation field 8 ... Direct X Line portion 9: subject portion, 10: scattered ray portion 11, 11 ': stimulable phosphor sheet 19, 19': stimulated emission light 21, 21 ': photomultiplier 26, 26' ... Amplifiers 27, 27 'A / D converter 28 Storage means 29 Operation means 50 Image processing means 60 Reproduction device 100 Prefetch means 100' Full reading means

Claims (2)

(57) [Claims] When a recording sheet is irradiated with radiation transmitted through the breast, a shadow of the breast is recorded in a shape protruding in a substantially semicircular shape from an edge of the recording sheet toward a center of the recording sheet. One or more subject portions, and a direct radiation portion formed so as to surround a substantially semicircular edge of the subject portion by irradiating the radiation directly onto the recording sheet without transmitting through the subject. When the recording sheet is irradiated with scattered radiation, a substantially semicircular shape of the subject portion is generated based on an image signal carrying a radiation image having a scattered radiation portion formed adjacent to the direct radiation portion. Candidate axis setting means for obtaining one or more candidates for the subject portion by capturing a change in the image signal at the periphery of the object portion; Position recognition means for recognizing the position of the subject portion on the radiographic image by determining whether each candidate is correct based on an average value of the corresponding image signal for each candidate. Breast image recording position recognition device. 2. The radiation transmitted through the breast is irradiated on the recording sheet, so that the shadow of the breast is recorded in a shape protruding in a substantially semicircular shape from the edge of the recording sheet toward the center of the recording sheet. One or more subject portions, and a direct radiation portion formed so as to surround a substantially semicircular edge of the subject portion by irradiating the radiation directly onto the recording sheet without transmitting through the subject. When the recording sheet is irradiated with scattered radiation, a substantially semicircular shape of the subject portion is generated based on an image signal carrying a radiation image having a scattered radiation portion formed adjacent to the direct radiation portion. Candidate axis setting means for obtaining one or a plurality of candidates for the subject portion by capturing a change in the image signal at the periphery of the object portion; A breast image recording position recognizing device comprising: a position recognizing means for recognizing the position of the subject on the radiographic image by determining whether each candidate is correct or false based on a geometric shape.