JPH048351A - Breast picture recording position-recognizing device - Google Patents

Abstract

PURPOSE:To accurately recognize a position of a body part by obtaining the proposed body part by catching a change of a picture signal in a side line of the body part and then deciding whether the proposed part is the aimed body part or not based on a mean value of the picture signal in each proposed region obtained in each proposal. CONSTITUTION:A binary signal is obtained assigning 1 to a signal of showing a direct X-ray part 8 and 0 to a signal of showing the other region by forming a first read picture signal Sp, holding the direct X-ray part 8, binary by a predetermined threshold value Th. When points A, B, C, where the binary signal becomes 1, are obtained, a body part 9 is recognized to exist in the corresponding side, and the body part 9 is decided for whether it is a true aimed body part 9 or not. When only the single body part 9 is proposed on a sheet 11, this candidature is judged to be a right body part 9 as it is without doubt. In the case of two candidature existing along two sides adjacent to each other, a mean value of the first read picture signal Sp in a region of these candidatures is obtained in each thereof, and the higher mean value is judged the true body part 9.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides information on recording on substantially the entire surface of a recording sheet obtained by reading substantially the entire surface of the recording sheet on which a radiation image of the breast is recorded in a partial area. The present invention relates to a breast image recording position recognition device that recognizes the position at which a radiographic image of a breast is recorded on a recording sheet based on an image signal carrying an entire radiographic image.

(Prior Art) It is practiced in various fields to read a recorded radiation image to obtain an image signal, perform appropriate image processing on the image signal, and then reproduce and record the image. For example, an X-ray image is recorded using an X-ray film with a low gamma value designed to be compatible with later image processing, and the X-ray image is read from the film on which it is recorded and converted into an electrical signal. By performing image processing on this electrical signal (image signal) and then reproducing it as a visible image in a photocopy, etc., it is possible to obtain a reproduced image with good image quality performance such as contrast, sharpness, and graininess. A system has been developed (see Japanese Patent Publication No. 61-5193).

The applicant has also proposed radiation (X-rays, α-rays).

When irradiated with β rays, γ rays, electron beams, ultraviolet rays, etc., a part of this radiation energy is accumulated, and then when irradiated with excitation light such as visible light, stimulable fluorescence exhibits stimulated luminescence depending on the accumulated energy. A radiation image of a subject such as a human body is photographed and recorded on a sheet of stimulable phosphor using a stimulable phosphor, and this stimulable phosphor sheet is scanned with excitation light such as a laser beam. The resulting stimulated luminescent light is read photoelectrically to obtain an image signal, and based on this image signal, a radiation image of the subject can be recorded on recording materials such as photographic materials, CRTs, etc. A radiation image recording and reproducing system that outputs a visual image has already been proposed (Japanese Patent Application Laid-Open No. 1983-1989)
No.-12429, No. 5B-11395.

No. 55-183472, No. 5B-104Ei45,
No. 55-118340, etc.).

This system has the practical advantage of recording images over a much wider radiation exposure range than conventional radiographic systems using silver halide photography. In other words, in a stimulable phosphor, it is recognized that the amount of emitted light that is stimulated to emit light due to excitation after accumulation is proportional to the amount of radiation exposure over an extremely wide range.
Therefore, even if the amount of radiation exposure varies considerably due to various imaging conditions, the amount of stimulated luminescence emitted from the stimulable phosphor sheet can be read by the photoelectric conversion means by setting the reading gain to an appropriate value. By converting the radiation image into an electric signal and using this electric signal to output the radiation image as a visible image to a recording material such as a photographic light-sensitive material or a display device such as a CRT, a radiation image that is not affected by fluctuations in radiation exposure amount can be obtained. be able to.

In the above system, the stimulable phosphor sheet is scanned in advance with a low-level light beam before obtaining an image signal by reading it under optimal reading conditions depending on the dose of radiation applied to the stimulable phosphor sheet. Pre-reading is performed to read the outline of the radiation image recorded on this sheet, the pre-read image signal obtained by this pre-reading is analyzed, and then the above sheet is irradiated with a light beam of a higher level than the light beam used during the above-mentioned pre-reading. There is also a system configured to perform main reading to obtain an image signal by scanning the radiation image and reading it under the optimal reading conditions for this radiation image (Japanese Patent Application Laid-open No. 5867240, No. 5).
No. 8-67241, No. 58-67242, etc.).

Here, reading conditions are a general term for various conditions that affect the relationship between the amount of stimulated luminescence light and the output of the reading device during reading, such as reading gain, scale factor, or , the power of excitation light during reading, etc.

Also, the high level and low level of the light beam are, respectively.
If the intensity of the light beam irradiated per unit area of the sheet or the intensity of stimulated luminescence light emitted from the sheet depends on the wavelength of the light beam (has a wavelength sensitivity distribution), It refers to the weighted intensity after weighting the intensity of the light beam irradiated per unit area of the sheet with the wavelength sensitivity.As a method of changing the level of the light beam, it is possible to methods to use, methods to change the intensity of the light beam itself emitted from a laser light source, methods to change the intensity of the light beam by inserting or removing an ND filter, etc. on the optical path of the light beam, methods to change the beam diameter of the light beam. How to change the scanning density,
Various known methods can be used, such as a method of changing the scanning speed.

In addition, regardless of whether the system performs this pre-reading or the system that does not, the obtained image signal (including the pre-read image signal) is analyzed and the optimal image processing conditions are determined when applying image processing to the image signal. Some systems let you decide. The term "image processing conditions" as used herein is a general term for various conditions under which an image signal is subjected to processing that affects the gradation, sensitivity, etc. of a reproduced image based on the image signal. The method of determining the optimal image processing conditions based on this image signal is not limited to systems using stimulable phosphor sheets, and for example, image signals are obtained from radiation images recorded on recording sheets such as conventional X-ray films. It is also applied to the system.

When photographing and recording radiation images on a recording sheet, it is important not to irradiate radiation to parts of the subject that are not necessary for observation, or if radiation is irradiated to parts that are not necessary for observation, the radiation may be transferred from that part to the parts necessary for observation. Since scattered radiation enters and degrades image quality, use an irradiation field diaphragm to limit the radiation irradiation area so that the radiation is applied only to the necessary part of the subject and a part of the recording area (within the irradiation field). It is often done. Furthermore, within the irradiation field, in addition to the subject area where the subject is photographed and recorded, there is often a direct radiation area where the subject is directly irradiated with radiation that does not pass through the subject. Of these areas, only the subject area is required to obtain a reproduced image. Therefore, the subject area in the radiation image recorded on the entire surface of the recording sheet is recognized, and the image signal corresponding to the subject area is generated. By extracting the image signal, optimal reading conditions and image processing conditions can be determined based on the extracted image signal, thereby making it possible to obtain a reproduced image that is suitable for viewing. When recognizing a subject, for example, characteristics that appear on a radiographic image due to the structure of an imaging device that photographs the subject, a unique shape of the subject, and the like are often taken into consideration. For example, JP-A-6
Publication No. 1-170178 describes an X-ray image of a human breast, in which the breast is photographed in a substantially semicircular shape on a recording sheet, and X-rays are directly irradiated onto the recording sheet outside the semicircular arc. Taking advantage of the fact that the direct X-ray part is recorded,
A method is described in which the position of the subject on an X-ray image is recognized by detecting a change in the image signal at the boundary between the subject (breast shadow) and the direct X-ray region.

(Problem to be Solved by the Invention) However, there are cases where shadows of the left and right breasts are recorded on two recording sheets, and in this case,
If the method described in Publication No. 78 is used, in addition to the subject area, an area outside the irradiation area that is directly adjacent to the X-ray area and is irradiated with only scattered radiation may be mistakenly recognized as the subject area. In some cases, overwhelming reading conditions 1 image processing conditions are not required, and the final image obtained is of poor quality and is not suitable for viewing.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a breast image recording position recognition device that can more accurately recognize the recording position of a breast shadow (subject area) on a recording sheet.

(Means for Solving the Problems) In the first breast image recording position recognition device of the present invention, radiation transmitted through the breast is irradiated onto the recording sheet, so that the shadow of the breast is separated from the edge of the recording sheet. One or more object parts recorded in a substantially semicircular shape protruding toward the center of the recording sheet, and the radiation rays directly irradiating the recording sheet without passing through the object. a direct radiation part formed to surround a substantially semicircular edge of the part; and a scattered radiation part formed adjacent to the direct radiation part by irradiating the recording sheet with scattered radiation. candidate extracting means for obtaining one or more candidates for the object part by capturing a change in the image signal at a substantially semicircular edge of the object part based on an image signal carrying a radiation image; Position recognition that recognizes the position of the object part on the radiographic image by determining whether each candidate is correct or incorrect based on the average value of each candidate of image signals corresponding to the object part obtained as a candidate. It is characterized by comprising means.

Here, the above-mentioned "average value" is not limited to the average value determined by the arithmetic mean, but also the mean value determined by the arithmetic mean, the median value, (maximum value + minimum value)/average value of the secondary image signal. It suffices if it is an indicator.

Further, in the second breast image recording position recognition device of the present invention, radiation transmitted through the breast is irradiated onto the recording sheet, so that the shadow of the breast is approximately moved from the edge of the recording sheet toward the center of the recording sheet. One or more object parts recorded in a protruding semicircular shape, and a substantially semicircular edge of the object part by directly irradiating the recording sheet with the radiation without passing through the object. An image signal carrying a radiation image having a direct radiation part formed to surround the direct radiation part and a scattered radiation part formed adjacent to the direct radiation part by irradiating the recording sheet with scattered radiation. candidate extracting means for obtaining one or more candidates for the object portion by capturing changes in the image signal at a substantially semicircular edge of the object portion; and the object portion obtained as the candidate. The apparatus is characterized by comprising a position recognition means for recognizing the position of the subject part on the radiation image by determining whether each candidate is correct or incorrect based on the geometrical shape of the image.

(Function) The present invention has one or more object parts recorded in a substantially semicircular shape protruding from the edge of a recording sheet toward the center of the recording sheet, and radiation transmitting through the object. A direct radiation area is formed surrounding the approximately semicircular edge of the subject area by directly irradiating the recording sheet, and a radiation area adjacent to the direct radiation area is formed by irradiating the recording sheet with scattered radiation. The object is a radiographic image having a scattered radiation portion formed by

The first breast image recording position recognition device of the present invention recognizes the position of the subject more accurately by focusing on the fact that the amount of radiation applied to the subject and the scattered radiation section is different from each other. That is, the first breast image recording position recognition device of the present invention uses the method described in, for example, the above-mentioned Japanese Patent Laid-Open No. 81-170178 or the embodiments described below, based on the image signal carrying the radiographic image. After finding one or more candidates for the object part by capturing changes in the image signal at the approximately semicircular edge of the object part using a method such as Since the correctness of each candidate is determined based on the average value of the image signal, the position of the subject on the radiation image can be recognized more accurately.

Furthermore, the position of the subject can be recognized more accurately by focusing on the fact that the subject has a substantially semicircular shape. The second breast image recording position recognition device of the present invention obtains one or more candidates for the subject part in the same manner as the first breast image recording position recognition apparatus, and then obtains the subject part found as the candidate. Since the correctness or incorrectness of each candidate is determined based on the geometrical shape of the image, the position of the subject on the radiation image can be more accurately recognized, similar to 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. This photographing device uses the stimulable phosphor sheet described above.

A cassette 2 containing a stimulable phosphor sheet is placed on the imaging table 1, and the cassette 2 and a presser plate 3 made of an acrylic plate or the like clamp and compress the breast 4, which is the subject.
An X-ray source 5 disposed above the subject 4 emits X-rays through a cone tube 6 having a semicircular cross section.

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

There is a semicircular irradiation field 7 on the stimulable phosphor sheet 11, and within the irradiation field 7 there is a direct X-ray section 8;
There is a subject portion 9 surrounded by. Further, outside the semicircular irradiation field 7 consisting of the direct X-ray section 8 and the object section 9, there is a scattered radiation section 10 (dotted portion in the figure) in which scattered X-rays are recorded.

Here, along the straight line y of this X-ray image, the amount of energy accumulated and recorded in the stimulable phosphor sheet 11 (the value of the image signal when reading this accumulated and recorded image as described later) is calculated. and the density of the visible image reproduced based on the image signal) is plotted,
As shown on the right side of FIG. 2, a curve is obtained in which the energy amount of the direct X-ray section 8 is the largest, the energy amount of the subject section 9 is the second 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 incorporating an example of the breast image recording position recognition device of the present invention. This example is a system that uses a stimulable phosphor sheet and performs pre-reading.

The stimulable phosphor sheet 11 on which the X-ray image including the breast has been recorded in the imaging device (see Figure 1) is first scanned with a weak light beam to capture only a portion of the X-ray energy accumulated in the sheet 11. Pre-reading means 10 for performing pre-reading by emitting
0 predetermined position. The stimulable phosphor sheet 11 set at this predetermined position is conveyed (sub-scanned) in the direction of arrow Y by a sheet conveying means I3 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 transmitted to the motor 23.
A rotating polygon mirror 16 that is driven by and rotates at high speed in the direction of the arrow.
is reflected and deflected by a focusing lens 17 such as an fθ lens.
After passing through, the optical path is changed by a mirror 18, and the light enters the sheet 11, and is main-scanned in the direction of arrow X, which is substantially perpendicular to the direction of sub-scanning (direction of arrow Y). From the location on the stimulable phosphor sheet 11 irradiated with the light beam 15, stimulated luminescence light 19 is emitted in an amount corresponding to the accumulated and recorded X-ray image information, and this stimulated luminescence light 19 is It is guided by a light guide 20 and photoelectrically detected by a photomultiplier 21. The light guide 20 is made by molding a light-guiding material such as an acrylic plate, and is arranged so that the linear entrance end surface 20a extends along the main scanning line on the stimulable phosphor sheet 11. The photomultiplier 21 is attached to the injection end surface 20b formed in an annular shape.
The light-receiving surfaces of the two are combined. The stimulated luminescent light 19 that has entered the light guide 20 from the incident end surface 20a travels through the interior of the light guide 2Q by repeating total reflection, and then travels through the light guide 2Q through the exit end surface 20b.
The light is emitted from and received by the photo multiplier 21, and
A photomultiplier 21 converts the amount of stimulated luminescent light 19 representing a line image into an electrical signal.

The analog output signal S output from the photomultiplier 21 is logarithmically amplified by a logarithmic amplifier 26 and digitized by an A/D converter 27 to obtain a pre-read image signal SP. The pre-read image signal SP has a value proportional to the logarithm of the amount of stimulated luminescence light 19.

In the above-mentioned pre-reading, reading conditions such as the voltage value applied to the photomultiplier 21 and the amplification factor of the logarithmic amplifier 26 are set so that the X-ray energy accumulated in the stimulable phosphor sheet 11 can be read over a wide range. It is determined.

The obtained pre-read image signal SP is inputted to the storage means 28 and stored therein. Thereafter, the pre-read image signal SP stored in the storage means 28 is read out and inputted to the calculation means 29, and the calculation means 29 uses the pre-read image signal SP stored on the stimulable phosphor sheet 11 based on the input pre-read image signal SP. The object part in the X-ray image formed is recognized. When the object part is recognized, the reading conditions G1 for main reading, such as the voltage applied to the photomultiplier 21' and the amplification factor of the logarithmic amplifier 26', are determined based on the pre-read image signal S corresponding to this object part. is required.

The stimulable phosphor sheet 11' for which pre-reading has been completed is set at a predetermined position in 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 the above-mentioned pre-reading. An image signal is obtained under the reading conditions G defined by the main reading means 100'.
Since the configuration of is similar to the configuration of the above-mentioned pre-reading means 100, components corresponding to each component of the pre-reading means 100 are shown with a dash attached to the number used in the pre-reading means 100,
Explanation will be omitted.

The image signal S0 obtained by being digitized by the A/D converter 27' is sent to the image processing means 50.

The image processing means 50 performs appropriate image processing on the image signal SQ. The image signal subjected to this image processing is sent to a reproduction device 60, and an X-ray image based on this image signal is reproduced and displayed.

Next, a method for recognizing a subject portion based on the pre-read image signal SP using the calculation means 29 will be described.

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

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 an X-ray image in which the left and right breasts are recorded above and below the sheet 11. It represents an image. Here, in the X-ray image shown in Fig. 48,
Parts of two direct X-ray sections 8 formed to surround two approximately semicircular subject sections 9 are connected to each other.

Furthermore, in the X-ray image shown in FIG. 4C, of the two upper and lower direct X-ray sections 8, the upper direct X-ray section 8 in the figure is formed slightly shifted to the right side in the figure.

As shown in FIGS. 4A to 4C, sometimes only one breast, left or right, is photographed and recorded on the stimulable phosphor sheet 11, and the two breasts on the stimulable phosphor sheet 11 facing each other The left and right breasts may be recorded so as to project approximately semicircularly from the sides (in this case, the top and bottom sides) toward the center of the stimulable phosphor sheet 11. Furthermore, as shown in Fig. 4C, the direct X-ray section 8 may be recorded slightly shifted from the standard position, and although not shown here, the subject section 9 may be recorded slightly shifted. .

Here, the pre-read image signal SP directly carrying the X-ray unit 8 has a large value as shown in FIG. 1 for each signal directly representing the X-ray section 8 by binarizing it with . Signals representing other regions are assigned 0 to obtain binary signals.

Next, based on this binary signal, a binarized X-ray image (
Hereinafter, each side 11a, 11b, 11c, 11d (fourth
(see Figures A to 4C), each midpoint Ca, Cb.

A search is made for a point where the binary signal becomes 1'' from Cc and Cd toward the opposing sides. For example, in a search starting from the midpoint Ca of the lower side 11a in FIG. 4A, point A is found as the point where the binary signal becomes 1'. In this way, if the point where the binary signal becomes 1° before reaching the opposite side is found, then go back a distance d from that point,
Next, the midpoints Ca, Cb, Cc, Cd, which were the starting points
When searched parallel to each side 11a, llb, 11c, lld where exists, two points (points B and C in the search starting from midpoint Ca in Fig. 4A) at which the binary signal is 1° are found. Desired. When three points (points A, B, and C) at which the binary signal becomes 1' are determined in this way, it is recognized that the subject portion 9 exists on the side corresponding to the three points. Note that after this, it is determined whether or not the subject part 9 obtained as described above is the true subject part 9, so the subject part 9 obtained here is We will refer to them as "candidates."

In the X-ray image shown in FIG. 4A, only one candidate for the object part 9 is found on the side 11a side, and in the X-ray image shown in FIG. The candidates for
For the line image, the three sides 11a, l], b.

It is recognized that there is a candidate for the subject portion 9 at the position corresponding to .lie. In this embodiment, the function of obtaining the above-mentioned candidates in the calculating means 29 shown in FIG. 3 is considered to be an example of the candidate extracting means according to the present invention.

FIG. 5 is a diagram schematically showing the arrangement positions on the sea 1-11 of candidates for the subject portion 9 determined as described above.

The mouth shown in the figure represents the sheet (the entire X-ray image), and the O mark represents the position of the above candidate.

As shown in the group in FIG. 5(a), when only one candidate for the subject portion 9 is found on the sheet 11, this candidate is determined to be the correct subject portion 9 without any doubt.

2 adjacent to each other as shown in the group in Figure 5(b).
If there are two candidates along one side, the average value of the pre-read image signal Sp in each candidate area is calculated for each candidate, and the one with the higher average value is determined to be the true object part. be judged.

2 facing each other as shown in the group in Figure 5(C)
If there are two candidates along one side, calculate the average value for each candidate of the pre-read image signal S, and if these average values or almost similar values exist, the left and right breasts It is determined that the recorded X-ray image is the true object part 9, that is, the two candidates are judged to be the true object part 9, and when these average values are significantly different from each other, the one with the larger value is determined to be the true object part 9. to decide.

Furthermore, when three candidates are obtained as shown in FIG. 5(d), the first average value of the pre-read image signals Sp corresponding to the two candidates obtained along the mutually opposing sides is , the second average value of the pre-read image signal S corresponding to the remaining one candidate, and the larger of these two average values is adopted. That is, if the first average value is larger, it is determined that the two candidates found along the opposite sides are the true subject portion 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. Note that if the first average value is larger, instead of immediately determining that the two candidates found along the opposite sides are the true subject portion 9 as described above, the first average value described above is determined. As in the case of the group in Figure 5 (C), find the average value of each of these two candidates,
If these two average values have almost the same value, it is determined that both of these two candidates are true object parts 9, and if these two average values deviate greatly from each other, the value It may be determined that the larger one is the true subject portion 9.

In addition, when four candidates are found as shown in FIG. The average value of the read image signal S is determined, and the two candidates with larger average values are determined to be the true subject portion 9.

In this case as well, instead of immediately determining that the two candidates with larger average values are the true subject,
The average value is further calculated for each of the two candidates with the larger average value, and if these two average values have almost the same value, both of these two candidates are considered to be the true subject part 9. If the two average values are significantly different from each other, it may be determined that the one with the larger value is the true subject portion 9.

In this embodiment, the I7A calculation means 2 shown in FIG.
9, the pre-read image signal S in each candidate area is
The function of calculating the average value of P and determining whether each candidate is a true object part based on the average value is an example of the position recognition means referred to in the first breast image recording position recognition device of the present invention. It is considered that.

As described above, once the subject is recognized by capturing the change in the pre-read image signal SP at the approximately semicircular edge of the subject 9, it is determined whether or not the subject is the true subject. As a result, the true position of the subject can be accurately determined.

- Once a subject is recognized, the method of determining whether or not the subject is a true subject is not limited to the determination method based on the average value of the pre-read image signal SP as described above; The determination may be made based on the geometrical shape of the subject, which is approximately semicircular.

FIG. 6 is a diagram showing an X-ray image similar to FIG. 4B in order to explain an example of the determination method based on this geometric shape. Regarding this X-ray image, four candidates are obtained as shown in FIG. 5(e).

Here, the candidates found along side 11a and the side li
The candidates found along d will be explained.

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 is determined for a candidate found along the side 11a, and a point E is found for a candidate found along the side lid.

Also, for each candidate, one of the two points that touch the corresponding side is determined. That is, for example, a point F is found for a candidate found along the side 11a, and a point G is found for a candidate found along the side lid.

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 value signal is mainly 0°, it is determined that the candidate is the true object part.In other words, for the candidate along the side 11a, the binary signal on the line segment connecting the dot and point F is °0°
Therefore, the candidate along the side 11a is determined to be the true subject portion 9, and for the candidate along the side lid, the binary image on the line segment connecting points E and G is 1゛. side li
It is determined that the candidates along d are not the true subject portions 9. In this way, the position of the subject 9 can be more accurately recognized by extracting the true subject 9 from the candidates for the subject 9 based on the geometrical shape of the subject 9 which is approximately semicircular. I can do it.

Note that the determination based on the geometrical shape that the subject portion 9 is approximately semicircular is not limited to the above method; for example, after determining the point closest to the center of the sheet 11 for each candidate, Each side 11a, llb, corresponding to the candidate
lie, 11. Each midpoint of d Ca, Cb, Cc,
A semicircle centered on Cd and passing through the point closest to the center above (
For example, for the candidate corresponding to the side 11a in FIG. 7A, the semicircular arc 31 and for the candidate corresponding to the side lid, the semicircular arc K)
0' and 0' of the binary image corresponding to the area within the semicircle.
It may be determined whether the candidate is the true subject portion 9 by determining the appearance ratio of 1°, or any other method may be used as long as the determination is based on a geometric shape.

In the above embodiment, the function of recognizing the true subject part 9 based on the geometrical shape in the calculation means 29 shown in FIG. It is considered an example of a recognition means.

The calculation for determining the candidate for the subject portion 9 is not limited to the calculation method described above.

7A and 7B are diagrams showing X-ray images similar to FIG. 4A in order to explain another method of determining candidates for the subject portion 9.

FIG. 7A shows that the contour is obtained by searching from the midpoint Ca of the side 11a in directions of 45', 90°, and 135' with respect to the side 11a, and such calculations are performed for each side.
Candidates for the subject portion 9 may be obtained by performing the process for 1a, 11b, 11c, and 11d.

Further, in FIG. 7B, contour points of the subject portion 9 are obtained from the midpoint Ca of the side 11a in the same manner as the calculation method shown in the embodiment described above, and two points C near both ends sandwiching the midpoint Ca.
The contour points of the subject portion 9 are determined in the same way from a' and Ca''.In this case, the contour points are at most 9.
However, if only 8 or less points are found, it is determined whether or not the subject portion 9 exists based on a predetermined algorithm.

Note that it goes without saying that calculation methods other than those described above may be used, and the candidate extraction means of the present invention may be any calculation method that captures changes in image signals along the road of the subject, and is not limited to a specific calculation method. It is not something that will be done. Furthermore, in the above-described embodiment, the pre-read image signal SP was binarized to obtain a binary signal, but in order to obtain candidates for the subject part, the pre-read image signal SP is not generated, but is based on the original pre-read image signal SP. Of course, it is also possible to find candidates for the subject portion using the following methods.

Once the position of the subject is correctly recognized in this way,
Based on the pre-read image signal S corresponding to this object part,
The reading condition G1 for the actual reading is determined.

Here, a description has been given of a device that uses the calculation means 29 to determine the reading conditions for main reading, but during main reading, reading is performed under predetermined reading conditions regardless of the pre-read image signal SP. Based on the read image signal Sp, the image processing condition G2 for performing image processing on the image signal S0 in the image processing means 50 is determined, and the image processing condition G2 determined by the calculation means 29 is calculated as shown by the broken line in FIG. It may be input to the image processing means 50, or the calculation means 2
In step 9, both the reading conditions and the image processing conditions may be obtained.

Further, in the reading device shown in FIG. 3, the pre-reading means 100 and the main reading means 100' are constructed separately, but as mentioned above, the structure of the pre-reading means 100 and the main reading means 100' is time-dependent. Therefore, the pre-reading means 100 and the main reading means 100'
They may also be used together.

In this case, after pre-reading, the stimulable phosphor sheet 1
1 back once and scan again to read the book.

When the pre-reading means and the main reading means are used, it is necessary to switch the intensity of the light beam between the pre-reading and the main reading. Various methods can be used, such as a method of switching the intensity itself.

Furthermore, although the above embodiment has been described with respect to a radiation image reading device that performs pre-reading, the present invention can also be applied to an X-ray image reading device that immediately performs reading equivalent to the above-mentioned main reading without performing pre-reading. In this case, when reading, an image signal is obtained by reading under predetermined reading conditions, and based on this image signal, an image processing condition is determined by the calculation means. Considered when applying processing.

Further, although the above embodiment deals with an X-ray image of a breast stored and recorded on a stimulable phosphor sheet, the present invention is not limited to those using a stimulable phosphor sheet; for example, X-ray photosensitive silver It can also be adopted in systems using salt films and the like.

(Effects of the Invention) As explained in detail above, the first and second breast image recording position recognition devices of the present invention find candidates for the subject by capturing changes in the image signal along the path of the subject. After that, it is determined whether the candidate is the subject part based on the average value of the image signal within each candidate area obtained for each candidate or the geometrical shape of the subject part. Therefore, the position of the subject can be recognized correctly.

[Brief explanation of the drawing]

1 is a diagram showing an outline of an example of an X-ray imaging device for performing mammography; FIG. 2 is a diagram showing an example of an X-ray image taken by the XL imaging device shown in FIG. 1; The figure is a perspective view of an example of an XvA image reading device incorporating an example of the breast image recording position recognition device of the present invention. FIG. 5 is a diagram schematically showing the arrangement position of candidates for the object part 9 on the sheet, and FIG. Figures 7A and 7B are diagrams showing an X-ray image similar to Figure 4B to explain an example of a method for determining subject parts. 4A is a diagram showing an X-ray image similar to FIG. 4A; FIG. 1...Photographing stand 2...Case/saute containing stimulable phosphor sheet 3.
...Press plate 4...Breast 5...X-ray source
6... Cone tube 7... Irradiation field 8.
...Direct X-ray section 9...Subject section 10...Scattered radiation section 11.11'...Stormable phosphor sheet 19
．． 19 '... Stimulated luminescence light 21.21 '... Photo multiplier 26.26
'... Amplifier 27.27 '... A/D converter 28... Storage means 29... Arithmetic means 50.
...Image processing means 60...Reproduction device 100...
Pre-reading means 100'...Main reading means diagram

Claims (2)

[Claims] (1) A recording sheet in which a shadow of the breast is recorded in a substantially semicircular shape protruding from the edge of the recording sheet toward the center of the recording sheet by irradiating the recording sheet with radiation that has passed through the breast; one or more subject parts; a direct radiation part formed so as to surround a substantially semicircular edge of the subject part by directly irradiating the recording sheet with the radiation without passing through the subject; By irradiating the recording sheet with scattered radiation, a substantially semicircular side of the subject area is detected based on an image signal carrying a radiation image having a scattered radiation area formed adjacent to the direct radiation area. candidate extracting means for obtaining one or more candidates for the object part by capturing changes in the image signal at the edges; A breast image recording position recognition device comprising: position recognition means for recognizing the position of the subject on the radiographic image by determining whether each candidate is correct or incorrect based on a value. (2) A recording sheet in which a shadow of the breast is recorded in a substantially semicircular shape protruding from the edge of the recording sheet toward the center of the recording sheet by irradiating the recording sheet with radiation that has passed through the breast; one or more subject parts; a direct radiation part formed so as to surround a substantially semicircular edge of the subject part by directly irradiating the recording sheet with the radiation without passing through the subject; By irradiating the recording sheet with scattered radiation, a substantially semicircular side of the subject area is detected based on an image signal carrying a radiation image having a scattered radiation area formed adjacent to the direct radiation area. Candidate extracting means for determining one or more candidates for the object part by capturing changes in the image signal at the edge, and determining whether each candidate is correct or incorrect based on the geometrical shape of the object part found as the candidate. A breast image recording position recognition device comprising: position recognition means for recognizing the position of the subject on the radiographic image by determining.