JPH04341247A - Photographing posture discriminating device for radiation image of chest - Google Patents

Abstract

PURPOSE:To easily discriminate the photographing posture of the radiation image of the chest of a human body without being affected by photographing conditions and physical shapes. CONSTITUTION:A vertebral column position is detected in accordance with profile information in the direction crossing the vertebral column in a vertebral column position detecting section 21. At least one of the linearity of the vertebral column, the position of the vertebral column within the image, the positional relation between the vertebral column and a dropout part, and the symmetry of the right and left regions bisected by the vertebral column are analyzed in a characteristic analyzing section 22. Whether the photographing posture is a front face or side face is discriminated in a posture discriminating section 23 by utilizing the characteristic that the vertebral column in the front face image linearly exists approximately at the center of the image, the distance between the vertebral column and the drop-out part on the side of the chest is far and the image is approximately symmetrical to the center line with the vertebral column as an axis. Processing conditions are determined according to the posture in an image processing condition determining section 24. A image processing section 25 executes image processing upon receipt of this determination.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for determining the body position of radiographic images of a human chest, and more particularly to an apparatus that can automatically determine the body position of radiographic images of a human chest.

0002

2. Description of the Related Art Radiographic images such as X-ray images are often used for medical purposes, and methods of obtaining these radiographic images as electrical image signals include, for example, the following methods. In other words, the radiation that has passed through the human body as an object is absorbed by a certain type of phosphor, and then this phosphor is excited with light or thermal energy, thereby removing the radiation energy that the phosphor has accumulated due to the absorption. It emits fluorescence and detects this fluorescence with a photoelectric conversion element to electrically obtain radiographic image information.The radiographic image signal is digitized and then subjected to image processing such as gradation processing and spatial frequency processing. The images are then output to a CRT or the like for visualization (see Japanese Patent Application Laid-open No. 189853/1983).

By the way, in the processing stage before outputting the digital radiographic image signal as a visible image as described above, gradation processing and spatial frequency processing are performed as described above to create a visible image suitable for interpretation. However, even if the image data is of the same part of the human body, if the imaging position (orientation of the human body as the subject) is changed, the density of the region of interest will change in each reproduced image. Sometimes.

For example, when a human chest is photographed from the front in order to diagnose the thoracic vertebrae, the thoracic vertebrae, which is the region of interest, overlaps with the mediastinum, which is difficult for radiation to pass through, but when photographed from the side, the radiation This overlaps with the lung field, which is easily penetrated. Therefore, if such image data is processed under the same image processing conditions and then reproduced, the density of the thoracic vertebrae portion will be relatively low in the frontal image, and the density will be relatively high in the side image.

[0005] Therefore, there is a method and apparatus that automatically determines in what body position a chest radiation image is taken and performs image processing optimal for each body position.
Various proposals have been made in the past. There are two methods and devices for this: one uses the density histogram of image data, and the other uses the signal level distribution (hereinafter referred to as profile information) along a predetermined direction of the image in the image data. (Japanese Unexamined Patent Publication No. 1983
-262128, JP 63-262132, JP 63-262134, JP 63-2
62139, etc.), those for determining the resolution of bimodal peaks (Japanese Patent Application Laid-open No. 63-262129, Japanese Patent Application Laid-open No. 62139,
3-262135, etc.), those that perform function approximation (JP-A-63-106642, JP-A-63-26)
2130, JP 63-262131, JP 63-262137, JP 63-2621
(See Publication No. 38, etc.).

Furthermore, there are methods for determining representative values and characteristic values from density histograms (see Japanese Patent Laid-Open No. 63-106641, etc.), methods for calculating dispersion of density histograms (see Japanese Patent Laid-Open No. 63-262133, etc.), A method has been proposed that calculates the sum of signal values near the center of profile information in the left and right directions (see Japanese Patent Laid-Open No. 63-262136, etc.).

[0007]

[Problem to be Solved by the Invention] However, in the above method, even when using a density histogram,
Even when profile information is used, the problem is that it requires a large amount of calculation to automatically determine the position in which the image was taken. For example, a standard pattern for frontal image data and a standard pattern for side image data are obtained from a large amount of image data, and the degree of similarity between this standard pattern and data input later is examined (Japanese Unexamined Patent Publication No. 63-26
No. 2130, Japanese Patent Application Laid-Open No. 63-262137, etc.) requires the use of complicated techniques such as multiple regression analysis in order to obtain standard patterns, resulting in a large amount of calculation.

[0008] Furthermore, when determining the photographing position using the density histogram, the photographing position is determined by capturing the shape difference in the density histogram, but the density histogram of the frontal chest image data and the side view of the chest Since the difference in shape between the image data and the density histogram is small, errors in judgment are likely to occur. Furthermore, when determining the photographing position using profile information, if there is a lateral positional shift of the human body within the photographing range, the profile pattern based on the image data may change even if the photographing position is the same. Therefore, there is a problem in that it becomes impossible to ensure accuracy in determining the photographing body position.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide an apparatus that can accurately determine the imaging position of a subject in a chest radiation image with a small amount of calculation.

0010

[Means for Solving the Problems] Therefore, the apparatus for determining the imaging position of a chest radiographic image according to the present invention determines the imaging position of a chest radiographic image formed in accordance with the amount of radiation transmitted through the human chest. It is configured as shown in FIG. In FIG. 1, the vertebral column position detection means detects the vertebral column position in the image based on the image signal of the thoracic radiation image, and the vertebral column characteristic analysis means detects the linearity of the vertebral column, the vertebral column position in the image,
At least one of four spinal column characteristics is analyzed: the positional relationship between the spinal column and a predetermined area in the image, and the symmetry of the image around the spinal column. Then, the photographing body position determining means determines the photographing body position of the chest radiographic image based on the spinal column characteristics analyzed by the spinal column characteristic analyzing means.

[0011]

[Operation] That is, when viewed from the front (or back) of a human body, the vertebral column extends linearly approximately in the middle of the body, and an image that is approximately symmetrical about the vertebral column as an axis can be obtained. On the other hand, when viewed from the side, the vertebral column is located closer to the back than the middle of the body, and there is no symmetry around the vertebral column, but the vertebral column is curved. The imaging body position determination device for chest radiographic images according to the present invention detects the spinal column position in the image, and based on the result, determines the position of the spinal column so that the imaging position can be determined using the basic properties of the spinal column. The imaging body position is determined by analyzing at least one of linearity, position, positional relationship with a predetermined area, and symmetry, and comparing the analysis results with the basic properties.

0012

[Examples] Examples of the present invention will be described below. FIG. 2 showing one embodiment is a medical radiation image recording and reading device including a chest radiation image imaging body position determination device according to the present invention, which photographs a human chest M and images of the photographed chest M. The following description will be made assuming that a region of interest within the chest is diagnosed by reproducing the image.

Here, the radiation source 1 is controlled by the radiation control device 2 and emits radiation (
(Generally, X-rays) are irradiated. The record reading device 3 is equipped with a radiation image conversion panel 4 on a surface facing the radiation source 1 with the chest M interposed therebetween, and this conversion panel 4 converts the radiation transmittance distribution of the chest M with respect to the radiation dose irradiated from the radiation source 1. The energy according to this is accumulated in the stimulable phosphor layer, and a latent image of the chest M is formed therein.

The conversion panel 4 has a stimulable phosphor layer provided on a support by vapor phase deposition of the stimulable phosphor or coating of a stimulable phosphor paint, and the stimulable phosphor layer The layer is shielded or covered with a protective member to block out environmental influences and damage. As the stimulable phosphor material, for example, a material as disclosed in Japanese Patent Application Laid-Open No. 61-72091 or Japanese Patent Application Laid-Open No. 59-75200 can be used.

A light beam generator (gas laser, solid-state laser, semiconductor laser, etc.) 5 generates a light beam whose output intensity is controlled, and the light beam reaches the scanner 6 via various optical systems. There, the light is deflected, and the optical path is further deflected by the reflecting mirror 7, and the light is guided to the conversion panel 4 as stimulated excitation scanning light. The condenser 8 has a condensing end made of an optical fiber located close to the conversion panel 4 scanned with the stimulated excitation light, and has a condensing end that is proportional to the latent image energy from the conversion panel 4 scanned with the light beam. Receives stimulated luminescence of luminous intensity. 9 is a filter that allows only light in the stimulated emission wavelength range to pass from the light introduced from the condenser 8, and the light that has passed through the filter 9 is incident on the photomultiple 10, which corresponds to the incident light. photoelectrically converted into a current signal.

The output current from the photomultiplier 10 is current/
The voltage signal is converted into a voltage signal by a voltage converter 11, amplified by an amplifier 12, and then converted into digital data (a digital radiation image signal proportional to the amount of radiation transmitted) by an A/D converter 13. The digital image signals, which are proportional to the amount of radiation transmitted through each part of the subject, are sequentially subjected to image processing in the image processing device 14, and the image signals after image processing are transmitted to the printer 17 via the interface 16. There is.

Reference numeral 15 denotes a CPU that controls image processing in the image processing device 14, and performs various image processing (such as spatial frequency processing, enlargement and reduction) on the digital radiation image data output from the A/D converter 13. , move, rotate,
Statistical processing, etc.) are performed in the image processing device 14 to create a form suitable for diagnosis, and then output to the printer 17, so that the printer 17 can obtain a hard copy of the chest radiographic image. Here, in order to set appropriate processing conditions in the image processing, it is determined whether the imaging position of the chest radiation image is frontal or side, and image processing conditions are determined based on the determination result. I have to.

It should be noted that what is connected via the interface 16 may be a monitor such as a CRT, or may further be a storage device (filing system) such as a semiconductor storage device. Reference numeral 18 denotes a reading gain adjustment circuit, and this reading gain adjustment circuit 18 adjusts the light beam intensity of the light beam generating section 5, adjusts the gain of the photomultiple 10 by adjusting the power supply voltage of the high voltage power supply 19 for the photomultiple, and the current/voltage converter. 11 and amplifier 12 gain adjustment, and A/D converter 1
The input dynamic range of step 3 is adjusted, and the reading gain of the radiation image signal is comprehensively adjusted.

The portion of the image processing device 14 involved in determining the photographing body position according to the present invention is specifically constructed as shown in FIG. The digital radiographic image signal of the chest M photoelectrically read from the stimulable phosphor layer of the conversion panel 4 is first inputted to the spinal column position detection section 21 as a spinal column position detection means, and here, The spinal column position in the chest radiation image is detected based on the signal level distribution (profile information) at .

The detection result of the spinal column position by the spinal column position detection section 21 is output to the characteristic analysis section 22 as a spinal column characteristic analysis means, where the detection result of the spinal column position is analyzed. The above analysis analyzes the characteristics of the vertebral column in a chest image that are known in advance, including the straightness of the vertebral column, the position of the vertebral column in the image, the positional relationship between the vertebral column and a predetermined area in the image, and the axis of the vertebral column. At least one of the four symmetries of the image is analyzed.

[0021] Body position discriminating section 23 as photographing body position discriminating means
Then, based on the analysis results in the characteristic analysis section 22, the imaging body position is determined to determine whether the chest radiographic image is a front view or a side view. Then, in the image processing condition determining section 24,
Based on the determined photographing body position, conditions for image processing such as gradation processing are determined in accordance with each photographing body position. The image processing section 25 performs image processing such as gradation processing on the chest radiographic image signal according to the conditions determined by the image processing condition determining section 24, and outputs the processed signal to the printer.

The image signals used in the spinal column position detection section 21, characteristic analysis section 22, body position discrimination section 23, and image processing condition determination section 24 other than the gradation processing section 23 are based on all pixels read by the recording/reading device 3. There is no need to use numbers;
The process of body position determination and gradation processing condition determination may be simplified using an image signal thinned out from the original image signal. In addition, body position discrimination and image processing conditions are determined based on image signals obtained by "pre-reading" as disclosed in JP-A-58-67240, and "main reading" is performed according to the determined processing conditions. The obtained image signal may be processed. The above-mentioned "pre-reading" refers to reading image signals by stimulating light emission with excitation light of lower energy than "main reading" prior to "main reading" used for observation and interpretation; After determining the image processing conditions based on the image signal, the image signal obtained in the "book reading" is subjected to image processing.

Next, a detailed description will be given of the determination of the photographing body position according to the present invention performed in the image processing device 14 whose detailed configuration is shown in FIG. First, the spinal column position detection unit 21 detects the spinal column position in the chest radiation image by detecting the signal level distribution (profile information) in the direction across the spinal column. In this embodiment, it is assumed that the vertical direction of the image always coincides with the vertical direction of the human body.

Detection of the spinal column position using projection as profile information is performed as follows. For example, as shown in FIG. 4 or 5, a plurality of strip regions are set vertically in the direction across the spinal column, and for each strip region, the integrated value (average value) of the signals in the pixel rows arranged in the vertical direction is A projection is created as profile information indicating how it changes in the horizontal direction, and in each of the projections created for each strip area, the horizontal position in the pixel row where the signal level becomes the minimum point is detected.

That is, in a thoracic radiographic image, the radiotransmittance is generally lowest in bone parts, especially in the spinal column (thoracic vertebrae), so the signal level distribution in the direction across the spinal column is the smallest. can be regarded as the point where it intersects the spinal column. Note that when a plurality of minimum points are detected, it is preferable to specify the minimum point closest to the center in the lateral direction as the point that intersects the spinal column. Furthermore, in the case where a plurality of band-like regions are set in the longitudinal direction as described above, it is preferable that the range from the neck to approximately the diaphragm is set as the region setting region.

[0026] As described above, if the spinal column position is detected as the minimum point of the projection in each of the plurality of strip-shaped regions set in the vertical direction, the line connecting the detection points in each strip-shaped region indicates the spinal column. Therefore, the two-dimensional position of the spinal column in each image is determined by directly connecting the discretely found spinal column points with a straight line or by approximating them using a quadratic or cubic function.

When creating a profile as a signal level distribution of one pixel row in the horizontal direction, profiles are created at multiple locations in the vertical direction in the same manner as described above.
(See FIGS. 6 and 7), a spinal column point is determined as the minimum point in each profile, and a process is performed to connect the multiple determined spinal column points to detect the spinal column position in each image.

When the spinal column position is detected in the above manner, the characteristic analysis section 22 analyzes the detection results, and based on the analysis results, the body position discriminating section 23 determines whether the photographing position is frontal or lateral. Determine whether it is. First, when analyzing the straightness of the vertebral column, normally when the chest is photographed from the front, the vertebral column will be approximately straight, but when taken from the side, the vertebral column will be curved. If the spinal column is substantially straight, it can be determined that it is a frontal image, and if it is curved, it can be determined that it is a side image.

[0029] For example, the linearity determination is performed as shown in FIGS. 8 and 9.
As shown in , the upper and lower end positions of the part of the spinal column detected by the spinal column position detection unit 21 are connected in a straight line, and the area of the area surrounded by the line connecting the upper and lower ends with the straight line and the spinal column line is calculated. This can be done by determining whether the area is equal to or larger than a predetermined determination level. If the detected spinal column is substantially straight, the area becomes smaller, and as the curvature increases, the area increases, so if the area is equal to or greater than the predetermined determination level, the chest image is taken from the side; When it is less than the determination level, it can be determined that the image is from the front.

[0030] In addition to the above method, linearity can be determined by
As shown in FIGS. 10 and 11, this can also be done by finding a straight line that passes through a plurality of points above a plurality of detected spinal column points, and finding the deviation between the straight line and the spinal column. In this case too,
If the chest image is from the front, the deviation is small; if the chest image is from the side, the deviation is large; therefore, the imaging body position can be determined based on the amount of deviation. The deviation can be detected by integrating the distances from each spinal column point to the straight line, or by determining the area of a region surrounded by the spinal column line and a straight line passing through the plurality of upper points.

Furthermore, when connecting a plurality of spinal column points to be determined, when approximating them by a quadratic or cubic function, the degree of curvature of the spinal column is determined based on the coefficients of the approximate function formula, and the degree of curvature is determined by determining the degree of curvature of the spine. In some cases, it may be determined that the image is a side image. On the other hand, the photographing body position (front or side) can also be determined by analyzing the position of the spinal column in the image. That is, since images are generally taken so that the subject is located in the center of the image area, when a chest radiographic image is taken from the front, the spinal column is located approximately in the center of the image,
In the case of lateral imaging, the spinal column near the back side is positioned laterally from the center of the image area, and the lateral position of the spinal column is either approximately the center of the image or a position displaced laterally. The photographing position can be determined depending on whether the

[0032] To determine whether the spinal column is located approximately at the center of the image, the average value of the spinal column coordinate values in the horizontal axis direction is calculated, and the deviation between the average value and the value corresponding to the center position is detected. When the amount of deviation is small, it is determined that the image is a front image, and when the deviation from the center is a predetermined level or more, it is determined that it is a side image. Furthermore, the imaging position can also be determined by analyzing the positional relationship between the spinal column and a predetermined area within the image.

That is, in a frontal image of the chest, the spinal column is located approximately at the center of the human body, and in a side image, the spinal column is located not in the center but on the side closer to the back, so that radiation does not pass through the human body. If the area is set as the predetermined area, the distance from the spine to the exposed area is relatively large in the front view (excluding the exposed areas of the neck and shoulders).
In contrast, in the case of the sides, the distance from the spinal column to the clear part on the back side is shorter. Therefore, the distance from the spinal column to the bare part (
It is also possible to determine whether the photographed body position is frontal or sideways by analyzing the positional relationship between the spinal column and the exposed part.

To analyze whether the spinal column is close to a clear part, in order to exclude the clear parts of the neck and shoulders in the front image, for example, in the lower half of the image, from the left and right sides of the spinal column in the transverse direction The distance to the clear part is determined at multiple locations, and the shortest one is detected. Then, the shortest distance is compared with a predetermined value, and if it is less than the predetermined value, it is assumed that the shortest distance has been detected as the distance between the bare part on the back side and the spinal column, and the shooting position is lateral side. If the shortest distance is a relatively large value corresponding to the distance from the center to the side of the front image, it is determined that the image is a front image (see FIGS. 12 and 13).
.

[0035] In addition to the above-mentioned method, analysis of whether the spine is close to the clear part can be carried out using the average of the horizontal coordinate values of the spinal column and the lateral direction of the boundary part (edge) between the clear part and the human body. It is also possible to compare the coordinate values with the average and make a determination based on the deviation between the two. Here, the boundary between the transparent part and the human body can be determined by calculating the differential value of the profile in the horizontal axis direction, and determining the points located on both sides of the peak value of the differential value as the boundary. In addition, in identifying the clear part, a histogram of the chest image signal is created as shown in Fig. 14, and the peak part near the maximum signal of this histogram is recognized as corresponding to the signal of the clear part. By recognizing a portion of a predetermined signal width near the maximum signal of the histogram as a signal value corresponding to a clear part, a clear part in an image can be specified.

[0036] Furthermore, the imaging position can also be determined by analyzing the symmetry of an image divided into left and right halves by the spinal column. When the human body is viewed from the front, the left and right sides are approximately symmetrical about the spinal column, but when viewed from the side, the left and right symmetry about the spinal column disappears. By setting it as an axis of symmetry and analyzing whether there is left-right symmetry, it becomes possible to determine whether the photographed body position is frontal or sideways.

Analysis of such symmetry is shown in FIGS. 15 and 16.
This can be done by analyzing the symmetry of the profile information around the spine point, as shown in . That is, profiles in the horizontal axis direction at multiple locations are created, signal differences are determined between pixels equidistant to the left and right with the spinal column as the center in the horizontal axis direction, and the average of the absolute values of the signal differences is determined. The left and right symmetry around the spinal column can be judged by whether or not the mean value is greater than a predetermined value. If the average value is less than the predetermined value, the left and right sides are approximately symmetrical about the spinal column, and the chest image is a frontal image. When the average value is large, it is determined that the image has no left-right symmetry and is taken from the side.

The symmetry of the left and right regions around the spinal column can be determined by comparing and analyzing the signal levels of pixels at symmetrical positions, as described above, or by Analysis can also be performed by creating a histogram for each of the left and right image regions that are divided into two, and comparing the variance values of the histograms in the left and right regions. In a frontal chest image, the left and right regions divided by the spinal column are approximately symmetrical, so the histograms for the left and right regions are also created to have approximately the same shape. In contrast, in the lateral image, one area divided by the spinal column contains a thick part containing internal organs such as the lungs, whereas the other area contains only a thin part between the spinal column and the back. In the region containing the internal organs, the image signal is relatively widely distributed, whereas in the dorsal region, the signal level tends to be biased to a certain part, resulting in a dispersion of the left and right histograms. The values will be significantly different.

Therefore, if the variance values of the histograms created for the left and right areas divided into two by the spinal column are approximately equal on the left and right sides, the left and right sides are approximately symmetrical frontal images, and when the variance values are significantly different, the left and right areas are It can be determined that the side image has no symmetry. In this way, the position of the vertebral column is detected in the image, and based on the detection results, the linearity of the vertebral column, the position of the vertebral column in the image, and the positional relationship between the vertebral column and a predetermined area (blank area) in the image are determined. , the imaging position can be determined by analyzing any one of the four spinal column characteristics, such as the symmetry of the image around the spinal column, and in particular, the straightness of the spine or the symmetry of the image When determining the photographing position by analyzing the position of the patient, the photographing position can be determined relatively easily without the need for complicated calculations. In addition, since the vertebral column in the human thorax is used as a reference, and its position and shape, as well as its positional relationship with the exposed part and left-right symmetry, are determined, the accuracy is less affected by body shape or imaging conditions. Good position discrimination is possible.

However, considering the unique cases shown in FIGS. 21 to 23, among the four spine characteristics analysis, the straightness of the spine or the position within the image of the spine is the easiest to calculate. There is a possibility of misdiagnosis when using the analysis results, and although the calculation becomes more complicated, it is possible to analyze the positional relationship between the spinal column and a predetermined area (blank area) in the image, or the symmetry of the image around the spinal column. It is desirable to use a combination of the four spinal column characteristics for discrimination.

The example shown in FIG. 21 shows a case where a patient with scoliosis is photographed from the front. In this case, although the degree of curvature of the spinal column is smaller than the degree of curvature of the spinal column in the side image, the straightness of the spinal column is analyzed and the photographing position is determined. When determining the degree of curvature, it becomes difficult to optimally set a threshold value for determining the degree of curvature, which may lead to erroneous determination. Therefore, in order to accurately determine the imaging position even in a chest image as shown in FIG.
It is preferable to analyze characteristics other than the straightness of the spinal column.

However, in a lateral chest image, as shown in FIG. 22, there are cases where the spinal column is located approximately in the center of the image; conversely, in a frontal chest image, the spinal column is located extremely to the side. There may be cases where the image is taken out of alignment, so
It is not very desirable to determine the imaging position based only on the position of the spinal column in the image. Therefore, considering the unique cases shown in Figs. 21 and 22, it is necessary to analyze either the positional relationship between the spinal column and a predetermined area (blank area) in the image, or the symmetry of the image around the spinal column. However, as shown in FIG. 23, it is assumed that one lung has been removed or shrunk, and in this case,
Since the symmetry of the left and right regions around the spinal column will be impaired, the accuracy of imaging body position determination based on symmetry analysis will deteriorate. It is most desirable to analyze the positional relationship between the image and a predetermined area (blank area) in the image.

However, the spinal column and a predetermined area in the image (
When analyzing the positional relationship with the vertebral column (the clear part), the calculations are more complicated than when analyzing the position in the image of the spinal column. The positions of the spinal column and the predetermined area (blank area) in the image are analyzed separately, and if the determination of the imaging position based on the respective analysis results is not equal, more complex calculations are required. It is preferable to analyze the relationship and the symmetry of the image around the spinal column so that the imaging position can be determined through as simple an analysis as possible.

In addition, in each of the above-mentioned analyzes of the four spinal column characteristics, instead of determining the imaging position from the analysis results as either front or side view, fuzzy inference etc. are used to determine whether the front image or The probability that the image is a side image may be set as a numerical value. If a definitive discrimination result cannot be obtained from the above-mentioned certainty, the simple analysis (linearity, position within the image) may be shifted to a more complex analysis (positional relationship, symmetry), or multiple analyzes may be performed. The imaging position may be finally determined by comprehensively determining the determination results of spinal column characteristics (the probability that the image is a frontal image or a side image).

Furthermore, the final body position discrimination result is not clearly indicated as either the front or the side, but is expressed in an ambiguous manner (membership value in fuzzy inference).
Alternatively, unknown discrimination results may be provided in addition to the front or side faces. When the imaging position of the chest radiographic image is determined to be frontal or lateral as described above, the image processing condition determination unit 24 uses the determined imaging position as at least information, preferably the signal level of the region of interest. The conditions for image processing such as gradation processing and spatial frequency processing are determined while referring to the above, and the image processing unit 25 is caused to perform image processing in accordance with this determination.

[0046] The chest radiation image signal that has been subjected to image processing based on the processing conditions set based on the imaging body position determination is as follows:
As mentioned above, it may be immediately made into a hard copy by the printer 17, but it may also be reproduced on a CRT, or
Alternatively, it may be temporarily stored in a filing system and read out when necessary to make a hard copy or display it on a CRT.

When storing chest radiation images in a filing system, it is preferable to store information on the imaging position in correspondence with each chest image signal, and the determined results are not necessarily used to determine image processing conditions. It does not have to be the intended purpose, and the image signal before image processing may be stored together with the information on the imaging position. Furthermore, in this example, the chest radiation image signal photoelectrically read from the stimulable phosphor layer is subjected to gradation processing, but the present invention is not limited to image reading using the stimulable phosphor. , or other two-dimensional radiation detectors may be used. For example, on a silver halide film that records chest radiographic images,
It may be configured such that light from a light source such as a laser or a fluorescent lamp is irradiated to obtain transmitted light through the silver halide film, and the transmitted light is photoelectrically converted to obtain a chest radiation image signal.

[0048]

Effects of the Invention As described above, according to the apparatus for determining the imaging position of chest radiographic images according to the present invention, the imaging position can be easily determined by utilizing the characteristics of the spinal column whose position can be easily detected. For example, when determining image processing conditions based on body position determination, it is possible to improve diagnostic performance in medical applications by setting optimal processing conditions. There is an effect that can be achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of the present invention.

FIG. 2 is an overall system block diagram showing one embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of an image processing section in the embodiment.

FIG. 4 is a diagram showing detection of spinal column position based on profile information.

FIG. 5 is a diagram showing detection of spinal column position based on profile information.

FIG. 6 is a diagram showing detection of spinal column position based on profile information.

FIG. 7 is a diagram showing detection of spinal column position based on profile information.

FIG. 8 is a diagram showing straightness analysis of the spinal column based on area comparison.

FIG. 9 is a diagram showing straightness analysis of the spinal column based on area comparison.

FIG. 10 is a diagram illustrating linearity analysis of the spinal column based on deviations from linear approximation.

FIG. 11 is a diagram showing linearity analysis of the spinal column based on deviations from a straight line approximation.

FIG. 12 is a diagram showing an analysis of the positional relationship between the bare part and the spinal column.

FIG. 13 is a diagram showing an analysis of the positional relationship between the bare part and the spinal column.

FIG. 14 is a diagram illustrating identification of a transparent portion using a histogram.

FIG. 15 is a diagram showing symmetry analysis using profile information.

FIG. 16 is a diagram showing symmetry analysis using profile information.

FIG. 17 is a diagram showing histograms for each left and right region divided into two by the spinal column.

FIG. 18 is a diagram showing histograms for each left and right region divided into two by the spinal column.

FIG. 19 is a diagram showing histograms for each left and right region divided into two by the spinal column.

FIG. 20 is a diagram showing histograms for each left and right region divided into two by the spinal column.

FIG. 21 is a state diagram showing the state of the spinal column in the case of scoliosis.

FIG. 22 is a state diagram showing when the spinal column position is centered in the side image.

FIG. 23 is a state diagram showing a state in which one lung is removed in a frontal image.

[Explanation of symbols]

21　　　Spine position detection unit 22 Characteristic analysis section 23 Body position determination unit 24 Image processing condition determination section 25 Image processing section

Claims (1)

[Claims] Claims: 1. A body position determination device for photographing a chest radiation image formed in accordance with the amount of radiation transmitted through the chest of a human body, the apparatus detecting a spinal column position in the image based on an image signal of the chest radiation image. Based on the spinal column position detecting means and the detection result of the spinal column position by the spinal column position detecting means,
Spinal column characteristics that analyze at least one of four spinal column characteristics: straightness of the spinal column, position of the spinal column in the image, positional relationship between the spinal column and a predetermined area in the image, and symmetry of the image around the spinal column. A photographing position for a chest radiographic image, comprising: an analysis means, and a photographing position discriminating means for determining the photographing position for a chest radiographic image based on the spinal column characteristics analyzed by the spinal column characteristic analysis means. Discrimination device.