JP2000157519A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly and automatically judge the direction of images and to process the images. SOLUTION: An irradiation field area is recognized by using the image data of radiation images and four areas Ard-1 to Ard-4 for direction discrimination close to the respective sides of the area Ard inside an irradiation field are set. Based on the cumulative histogram of the image data inside the respective areas for the direction discrimination, direction discrimination representative values are decided. The size relation of the direction discrimination representative values inside the respective areas for the direction discrimination becomes prescribed size relation corresponding to a photographing part. Thus, from information for indicating the photographing part and the size relation of the direction discrimination representative values, the direction of the image is discriminated depending on which is the area for the direction discrimination for maximizing or minimizing the direction discrimination representative value for instance. By generating the image data in a correct direction based on a discriminated result, deciding an image processing condition and processing the image, the radiation image suitable for a diagnosis is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus capable of automatically determining the direction of an image using an image signal of a radiation image.

[0002]

2. Description of the Related Art Conventionally, as a method for obtaining an image signal of a radiation image such as a human body X-ray image for diagnosing a disease, a method using a film digitizer or a stimulable phosphor detector is known.

In a method using a film digitizer,
A radiographic film that has been subjected to chemical development and fixing is irradiated with laser light, and the transmitted or reflected light is converted into an electrical signal using a photoelectric conversion means such as a photomultiplier, thereby producing a radiographic image. Is obtained.

In the method using a stimulable phosphor detector, when a part of radiation energy is accumulated and then irradiated with excitation light such as visible light, the stimulable phosphor emits stimulable light in accordance with the accumulated energy. A latent image of a radiation image of a subject is formed on a radiation image conversion plate having a stimulable phosphor layer formed on a flat support using a stimulable phosphor, and then irradiated with a laser beam or the like, thereby stimulating light emission. Is converted into an electric signal by a photoelectric conversion unit, and an image signal of a radiation image is obtained.

Further, an FPD (Flat Panel) which can obtain an image signal of a radiation image without condensing transmitted light, reflected light or stimulated luminescence as in the case of using a film digitizer or a stimulable phosphor detector. Detector) is also known.

In the method using the FPD, an image pickup panel is formed by arranging a plurality of detection elements two-dimensionally, and an image signal is generated based on the radiation dose detected by each detection element of the image pickup panel. Therefore, a radiation image with high sharpness can be obtained.

When displaying or outputting a radiographic image based on the image signal obtained in this way, image processing is performed so that the radiographic image can be easily viewed without being affected by changes in imaging conditions.

When this image processing is performed, for example, Japanese Patent Application Laid-Open
As disclosed in Japanese Patent No. 7578, a region of interest is set corresponding to the anatomical structure of a human body, and image processing conditions are determined based on image signals in the region of interest.

Here, when using a built-in type radiation image pickup apparatus in which the detector is fixed to the radiation image reading apparatus, the direction of the subject is fixed with respect to the detector, but the detector is not fixed to the apparatus. In the case of the cassette type, since the position of the detector can be freely changed according to the imaging region, the orientation of the subject with respect to the detector is not constant. For example, when a radiographic image of the front of the chest is taken, when the body shape is not obese, as shown in FIG. 15A, the image is taken so that the longitudinal direction of the imaging region is the vertical direction. When the body type is obese, as shown in FIG. 15B, imaging is performed such that the longitudinal direction of the imaging region is horizontal so that the chest does not protrude from the imaging region.

As described above, when the direction of the human body in the image is different, when the region of interest is set with the longitudinal direction of the photographing region being the vertical direction of the photographed image, the longitudinal direction of the photographing region is defined as the horizontal direction of the photographed image. In such a case, the region of interest cannot be properly set, and image processing cannot be performed correctly.

[0011] In addition, when a doctor makes a diagnosis or the like, the direction of the radiation image is usually, for example, the head of the human body is set to the upper side of the radiation image. It will be difficult.

For this reason, as disclosed in Japanese Patent Application Laid-Open No. 63-304378, it is determined whether the image is erect or rolled over by comparing the characteristic values of the vertical band and the horizontal band including the center of the image. A way to do that has been proposed.

[0013]

In the above-described method of judging rollover of an image disclosed in Japanese Patent Application Laid-Open No. Sho 63-304378, it is determined whether the image is upright or rollover. For example, it is not possible to determine the reverse of the image.

When the vertebra is photographed in the vertical direction and the pelvis is photographed in the horizontal direction as in the front image of the pelvis, the difference between the total value and the average value of the image signal levels is small. Therefore, there may be a case where it is not possible to determine whether the object is upright or overturning depending on the imaging part.

When the total value or average value of the image signal levels included in the band-shaped area changes due to the position of the subject shifting or tilting in the vertical direction or the horizontal direction, whether the object is erect or rollover is correctly determined. The judgment cannot be made.

Further, when the sum or average of the levels of the image signal is used as the characteristic value, when a pixel having a significantly different level of the image signal occurs due to a pixel defect, noise, or the like, the sum or the average of the image signal is changed by this pixel. Affected.

As described above, a case may occur where the orientation of the radiation image cannot be correctly determined. Therefore, even if the rollover determination method of the image disclosed in JP-A-63-304378 is used, the region of interest can be properly determined. And the image processing cannot be performed correctly. Further, when the orientation of the image cannot be determined correctly, the radiation image cannot be set to a direction suitable for diagnosis or the like.

Accordingly, an object of the present invention is to provide an image processing apparatus capable of correctly and automatically determining the direction of an image and performing image processing.

[0019]

An image processing apparatus according to the present invention is an image processing apparatus that performs image processing of a radiation image using image data of a radiation image generated based on radiation transmitted through a subject. An irradiation field recognizing means for recognizing an irradiation field area of radiation, an area setting means for setting a plurality of direction discriminating areas which do not overlap each other in the recognized irradiation field area, For each of them, a representative value determining means for determining a direction determination representative value of image data in the direction determination area, and a predetermined calculation is performed using the determined plurality of direction determination representative values, and a radiation image is determined based on the calculation result. Image direction discriminating means for discriminating the image direction of an image, and image data for performing image processing of a radiation image by determining image processing conditions based on the discrimination result and image data in the image direction discriminating means. Those having a data processing unit. Further, the image display means for displaying a radiation image using image data subjected to image processing by the image data processing means, the discrimination result of the image direction discriminating means, and the image processing conditions determined by the image data processing means, The apparatus includes an output unit for outputting to an external device in association with image data of an image, an imaging region information input unit for inputting imaging region information of a radiation image, and a correction information input unit for inputting image direction correction information.

According to the present invention, the irradiation field area is recognized using the image data of the radiation image, and the recognized irradiation field area is overlapped by a number corresponding to the number of directions for determining the direction of the radiation image. A plurality of direction discriminating areas without the mark are set. For example, when a substantially rectangular irradiation field area is recognized and four directions are determined, four direction discrimination areas are set near each side of the substantially rectangular irradiation field area. A direction discrimination representative value is determined based on the cumulative histogram of the image data in the set direction discrimination area, and a predetermined calculation is performed using the discrimination representative value. The orientation is determined. Based on the determination result, image data in a correct direction is generated to determine image processing conditions, and image processing including gradation processing and the like is performed. In addition, the determination of the direction of the radiation image and the determination of the image processing condition are performed using the input imaging region information, and the determination result of the direction of the radiation image is corrected by the image direction correction information. Further, the determination result of the orientation of the radiation image, the image processing condition, and the image data before the image processing are output in association with each other.

[0021]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a configuration of a radiation image capturing system. Radiation emitted from a radiation generator 10 passes through a subject 5 and is a cassette type radiation image reader (hereinafter, referred to as “radiation image reader”) 2.
The image is irradiated on the imaging panel of No. 0. In the radiation image reader 20, image data is generated based on the intensity of the irradiated radiation. In the controller 40, the radiation image reader 2
The display and output of a radiographic image with good image quality are performed using the image data supplied from 0.

FIG. 2 shows a configuration of the radiation image reader 20 using the FPD. The imaging panel 21 has a substrate having a thickness enough to obtain a predetermined rigidity, and a detection element 212- (1,1) that outputs an electric signal in accordance with the dose of the irradiated radiation is provided on the substrate. ~ 212- (m, n) are two-dimensionally arranged. Further, the scanning lines 215-1 to 215-m and the signal lines 216-1 to 216-n are arranged, for example, to be orthogonal.

The scanning lines 215-1 to 215 of the imaging panel 21
-m is connected to the scan drive circuit 24. The readout signal RS is sent from the scan drive circuit 24 to one of the scan lines 215-1 to 215 -m (p is one of 1 to m).
Is supplied, the electric signal SV corresponding to the dose of the radiation emitted from the detection element connected to the scanning line 215-p.
-1 to SV-n are output and supplied to the image data generation circuit 26 via the signal lines 216-1 to 216-n.

The detection element 212 may be any element that outputs an electric signal corresponding to the dose of the irradiated radiation.
For example, when a detection element is formed using a photoconductive layer in which an electron-hole pair is generated when radiation is irradiated and the resistance value changes, the amount of radiation generated in the photoconductive layer depends on the amount of radiation generated in the photoconductive layer. An amount of charge is stored in the charge storage capacitor, and the charge stored in the charge storage capacitor is supplied to the image data generation circuit 26 as an electric signal. The photoconductive layer desirably has a high dark resistance value, and is preferably amorphous selenium, lead oxide, cadmium sulfide, mercuric iodide,
Or, a photoconductive organic material (including a photoconductive polymer to which an X-ray absorbing compound is added) is used,
Particularly, amorphous selenium is desirable.

When the detecting element 212 is formed using, for example, a scintillator or the like that generates fluorescence when irradiated with radiation, a photodiode generates an electric signal based on the intensity of the fluorescent light generated by the scintillator. It may be supplied to the image data generation circuit 26.

The image data generation circuit 26 sequentially selects the supplied electric signals SV based on an output control signal SC from a read control circuit 28 described later, and converts them into digital image data DT. The image data DT is supplied to the reading control circuit 28.

The read control circuit 28 includes a memory 29 using a rewritable read-only memory (for example, a flash memory), an operation unit 30 for switching the operation of the radiation image reader 20, a detection of radiation irradiation. And a display unit 32 for displaying a captured radiographic image, completion of radiographic image preparation, and the like. The memory 29 stores image data DT from the image data generating circuit 26. It is. In addition, a scan control signal RC and an output control signal SC are generated based on an operation signal PS from the operation unit 30 and a sensor signal SS from the sensor 31 and supplied to the scan drive circuit 24 and the image data generation circuit 26. By controlling the supply of power from the unit 33 to the imaging panel 21, initialization of the imaging panel 21, a standby state of radiation irradiation, or reading of a radiation image is performed. The connector 3 connected to the read control circuit 28
4, a radiation irradiation end signal D from the radiation generator 10
The radiation image is also read when the FE is supplied. Note that the radiation image reader 20 is
Power is supplied to each of the circuits.

The image data DT obtained by the radiation image reader 20 is read from the memory 29 and read by the read control circuit 2.
8 to the controller 40. Or,
After the memory 29 is removed from the radiation image reader 20, it is mounted on the controller 40, and the image data DT is supplied to the controller 40.

Next, the configuration of the controller 40 is shown in FIG. CPU (C) for controlling the operation of the controller 40
The central processing unit 41 includes a system bus 42
And the image bus 43 and the input interface 47 are connected. The operation of the CPU 41 for controlling the operation of the controller 40 is controlled based on a control program stored in the memory 44.

A display controller 45, a frame memory controller 46, an output interface 48, a data read controller 49, a disk controller 50, and the like are connected to the system bus 42 and the image bus 43. C
The operation of each unit is controlled by the PU 41, and image data is transferred between the units via the image bus 43.

The frame memory 51 is connected to the frame memory controller 46, and the image data DT obtained by the radiation image reader 20 is stored via the data read controller 49 and the frame memory controller 46. . The image data stored in the frame memory 51 is read and supplied to the display control unit 45 and the disk control unit 50. The frame memory 51 may store the image data DT supplied from the radiation image reader 20 after the CPU 41 processes the image data DT.

An image display device 52 is connected to the display control unit 45, and a radiographic image based on the image data supplied to the display control unit 45 is displayed on the screen of the image display device 52. Here, when the number of display pixels of the image display device 52 is smaller than the number of pixels of the radiation image reader 20,
By thinning out and reading out the image data, the entire captured image can be displayed on the screen. In addition, if the image data of the area corresponding to the number of display pixels of the image display device 52 is read out, a captured image at a desired position can be displayed in detail.

From the frame memory 51 to the disk controller 5
When the image data is supplied to the disk controller 50, for example, the image data is read continuously and
The data is written into the O memory, and then sequentially recorded on the disk device 53.

Further, the image data read from the frame memory 51 and the image data read from the disk device 53 are transmitted to the external device 1 via the output interface 48.
00 can also be supplied.

In the image processing section 55, the radiation image reader 2
From 0, an irradiation field recognition process, a region of interest setting, an image orientation determination process, a normalization process, a gradation process, and the like of the image data DT supplied via the data read control unit 49 are performed. Further, frequency emphasis processing, dynamic range compression processing, and the like may be performed. Note that the image processing unit 55 may be configured to also serve as the CPU 41 to perform image processing or the like.

The input interface 47 is connected to an input device 54 such as a keyboard. By operating the input device 54, information for identifying image data obtained by imaging, imaging region information indicating an imaging region, imaging condition information indicating imaging conditions such as a tube voltage and a radiation dose of radiation, and the like. Is input.

As the external device 100 connected to the output interface 48, a scanning laser exposure device also called a laser imager is used. In this scanning laser exposure apparatus, the intensity of a laser beam is modulated by image data, exposed to a conventional silver halide photographic material or a thermal phenomenon silver halide photographic material, and then subjected to an appropriate development process to thereby obtain a radiation image. A hard copy is obtained.

Although the frame memory 51 stores the image data supplied from the radiation image reader 20, the CPU 41 may process the supplied image data before storing the image data. Further, the disk device 53 stores image data stored in the frame memory 51, that is, image data supplied from the radiation image reader 20, and image data obtained by processing the image data by the CPU 41, together with management information and the like. be able to.

A radiation image reader 2 using an FPD
Instead of 0, a radiation image reader 60 using a stimulable phosphor detector may be used. FIG. 4 shows a configuration in which a stimulable phosphor detector is used. The cassette stacker unit 61 can accommodate a plurality of cassettes 63 accommodating a radiation image conversion plate (hereinafter, referred to as “conversion plate”) 62. Is configured.

In this conversion plate 62, a stimulable phosphor layer is provided on a support by vapor deposition of a stimulable phosphor or application of a stimulable phosphor paint. It is shielded or covered by a protective member to prevent adverse effects and damage due to the environment. Energy according to the radiation transmittance distribution of the human body is accumulated in the stimulable phosphor layer of the conversion plate 62, and a latent image of a radiation image is formed.

Here, the conversion plate 62 after the radiation irradiation
When a cassette control signal STC, which will be described later, is supplied from the reading control unit 80 to the stacker drive control unit 64 in a state where the cassette 63 in which the cassette 63 is stored in the cassette stacker unit 61, the stacker control signal ST
C to generate a stacker drive signal STD for driving the cassette stacker 61, and
To supply. The stacker driving section 65 drives the cassette stacker section 61 based on the stacker driving signal STD.
Also, a plate transport control signal PTC
Is supplied to the plate transport control unit 66, the plate transport control unit 66 takes out the conversion plate 62 from the cassette 63 based on the plate transport control signal PTC and transports the conversion plate 62 to a predetermined position, or is taken out to a predetermined position. A plate transport drive signal PTD for storing the existing conversion plate 62 in the cassette 63 is generated and supplied to the plate transport section 67. The plate transport section 67 transports the conversion plate 62 based on the plate transport drive signal PTD. For this reason, a desired cassette is selected from the cassettes 63 stored in the cassette stacker unit 61 by the stacker control signal STC and the plate transport control signal PTC from the reading control unit 80, and the selected cassette is stored in the selected cassette. Conversion plate 62 can be used. An erasing section 68 is provided along the transfer position of the conversion plate 62. When the generation of the image data of the radiation image based on the latent image formed on the conversion plate 62 is completed, the conversion plate 62 is moved to the cassette 63. Is stored in the erasing unit 68, the erasing signal ER is sent from the reading control unit 80.
And the latent image formed on the stimulable phosphor layer of the conversion plate 62 is erased.

The light beam generator (gas laser, solid-state laser, semiconductor laser, etc.) 70 generates a light beam whose emission intensity is controlled based on the read control signal LC supplied from the read controller 80. This light beam reaches the scanning unit 71 via various optical systems, is deflected by the scanning unit 71, and further deflected the optical path by the reflection mirror 72 to the conversion plate 62 extracted from the cassette stacker unit 61. Guided as stimulating excitation scanning light.

The light-collecting end of the light-collecting body 73 formed of an optical fiber or a sheet-like light guide member is disposed close to the conversion plate 62 on which the stimulating excitation light is scanned. The conversion plate 62 is scanned by the beam.
Stimulable emission having a light emission intensity proportional to the energy of the latent image formed in the light source.

The filter 74 allows only light in the stimulating emission wavelength region from the light introduced from the light collector 73 to pass therethrough. The light passing through the filter 74 is incident on the photomultiplier 75.

The photomultiplier 75 generates a current signal corresponding to the incident light by photoelectric conversion. This current signal is supplied to the current / voltage converter 76 and converted into a voltage signal VS. Further, the voltage signal VS is supplied to the amplifier 77
After that, the data is converted into digital image data DT by the A / D converter 78. Here, by using a logarithmic conversion amplifying unit (log amplifier) as the amplifying unit 77, the subsequent processing of the image data can be easily performed. The image data DT obtained from the A / D converter 78 is supplied to the main CPU 90.

The reading control unit 80 includes a main CP (to be described later).
U (Central Processing Unit) 90 is connected,
Based on an operation control signal CT from the main CPU 90, generation of a stacker control signal STC, a plate transport control signal PTC, and an erasure signal ER, adjustment of the light beam intensity of the light beam generator 70, and adjustment of the power supply voltage of the high voltage power supply 81 for the photomultiplier. Gain adjustment of the photomultiplier 75, gain adjustment of the current / voltage conversion unit 76 and the amplification unit 77,
The adjustment of the input dynamic range of the A / D converter 78 is performed, and the reading of the radiation image and the comprehensive adjustment of the reading gain are performed.

An operation unit 91, an image processing unit 92, a storage device 93, an image display device 94, and an interface unit 95 are connected to the main CPU 90, and generate an operation control signal CT in accordance with the operation of the operation unit 91. Reading control unit 80
To supply. Further, the main CPU 90 supplies the supplied image data DT to the image processing unit 92. When the image data DT is supplied to the image processing unit 92, the image processing unit 92 performs an irradiation field recognition process, a region of interest setting, an image orientation determination process, a normalization process, a gradation process, and the like of the image data DT. Done. Further, frequency emphasis processing, dynamic range compression processing, and the like may be performed. It should be noted that the image processing section 92 may be configured to also serve as the main CPU 90 to perform image processing and the like.

Further, information for identifying image data obtained by imaging, imaging part information indicating an imaging part, and radiation tube voltage, radiation amount, and the like are operated by the operation unit 91 or a patient registration terminal 98 described later. Photographing condition information and the like indicating the photographing conditions are supplied to the main CPU 90.

Storage device 9 connected to main CPU 90
3 stores image data supplied from the A / D conversion unit 78, image data processed by the image processing unit 92, and the like. On the screen of the image display device 94 connected to the main CPU 90, a radiation image before image processing and a radiation image after image processing are displayed. Furthermore, the main CPU
Reference numeral 90 denotes a host computer 96, a diagnostic device 97, and a patient registration terminal 9 via an interface unit 95.
8 etc. are connected.

When a film digitizer is used, image data is generated by irradiating a radiographic film with a laser beam and converting the transmitted or reflected light into an electrical signal by a photoelectric means such as a photomultiplier. The image processing is performed using the image data by an image processing unit similar to the image processing units 55 and 92 described above.

Next, the operation will be described. When obtaining a radiation image of the subject 5, it is assumed that the subject 5 is located between the radiation generator 10 and the imaging panel 21 of the radiation image reader 20, and the radiation emitted from the radiation generator 10 And the radiation transmitted through the subject 5 is incident on the imaging panel 21.

When the power switch of the radiation image reader 20 is turned on, the image pickup panel 21 is initialized by the reading control circuit 28 and the like of the radiation image reader 20.
This initialization is for obtaining a correct electric signal corresponding to the radiation dose emitted from the imaging panel 21.

Imaging panel 21 in radiation image reader 20
Is completed, irradiation of radiation from the radiation generator 10 is enabled. Here, for example, a switch for irradiating radiation is provided in the radiation generator 10, and when this switch is operated, radiation is emitted from the radiation generator 10 toward the subject 5 for a predetermined time.

At this time, the radiation dose of the radiation applied to the imaging panel 21 of the radiation image reader 20 is modulated by the subject 5 because the degree of absorption of the radiation by the subject 5 differs. Detection element 212- (1,1) of imaging panel 21
At 212 to (m, n), an electric signal based on the radiation modulated by the subject 5 is generated.

In the radiation image reader 20, the sensor signal S
After determining the radiation irradiation end based on S, or when the radiation irradiation end signal DFE is supplied from the radiation generator 10, the reading control unit 2 of the radiation image reader 20
The reading of the radiation image is performed by the
9, the image data DT is written.

When the memory 29 is taken out of the radiation image reader 20 and attached to the controller 40 to read out the image data DT, or the image data DT written in the memory 29 is sent to the controller 40 via the reading control circuit 28. Is transmitted to the image data D
T is the data read control unit 49 or the frame memory control unit 4
6 and the like, and are stored in the frame memory 51. Using the image data stored in the frame memory 51, a radiation image can be displayed on the image display device 52.

The image data stored in the frame memory 51 is processed by the image processing unit 55 and supplied to the display control unit 45, or the image data on which the image processing has been performed is stored in the frame memory 51. By supplying the stored image data to the display control unit 45, the brightness, contrast, sharpness, and the like are adjusted, and a radiation image suitable for diagnosis or the like can be displayed. In addition, by supplying the image data subjected to the image processing to the external device 100, a hard copy of a radiation image suitable for diagnosis or the like can be obtained.

When the radiation image reader 60 using the stimulable phosphor detector is used, the radiation image reader 6
The 0 conversion plate 62 is irradiated with radiation modulated by the subject 5 in a state of being housed in the cassette 63, and a latent image based on the modulated radiation is formed.
Here, when the cassette 63 containing the conversion plate 62 on which the latent image is formed is stored in the cassette stacker 61,
Immediately, the conversion plate 62 is transported to a predetermined position to generate the image data DT. The conversion plate 62 on which the latent image is formed without generating the image data DT.
Is stored in the cassette stacker unit 61, and radiation images are sequentially taken using the new conversion plate 62, and thereafter,
A plurality of conversion plates 62 on which latent images are formed are sequentially taken out from the cassette stacker unit 61, and the taken-out conversion plates 62 are irradiated with a light beam to generate image data DT. The image data DT obtained in this way is subjected to image processing by the image processing unit 92 so as to obtain a radiation image suitable for diagnosis or the like.

Next, the image processing operation of the image processing section 55 will be described. Note that the image processing unit 92 and the image processing unit using the film digitizer perform the same image processing as the image processing unit 55, and the description of the image processing operation is omitted.

In the image processing unit 55, even if the distribution of the level of the image data output from the imaging panel 21 fluctuates due to the difference in the radiation dose, the image data is always obtained so that a stable radiation image can be obtained. DT normalization processing is performed. Further, even if the level distribution of the image data fluctuates, the gradation processing is performed on the normalized image data DTreg which is the image data after the normalization processing in order to obtain a radiation image having a density and contrast suitable for diagnosis and the like. Done.
Further, in the image processing unit 55, the normalized image data DTreg
Frequency enhancement processing to control the sharpness of the normalized radiographic image, and dynamic range to fit the entire radiographic image with a wide dynamic range within a concentration range that is easy to see without reducing the contrast of the fine structure of the subject A compression process may be performed.

By the way, when taking a radiographic image,
For example, to prevent radiation from being irradiated to a part not required for diagnosis, or to irradiate radiation to a part not required for diagnosis, radiation scattered in this part is incident on a part required for diagnosis. In order to prevent the resolution from decreasing, a part of the subject 5 and the radiation generator 1
A radiation non-transmissive substance such as a lead plate is placed at 0, and an irradiation field stop for limiting an irradiation field of the radiation to the subject 5 is performed.

When this irradiation field aperture is performed, if level conversion processing and subsequent gradation processing are performed using the image data of the irradiation field inside area and the irradiation field outside area, the image data of the outside irradiation field area will be used. Image processing of a portion required for diagnosis in the irradiation field is not properly performed.
For this reason, the image processing unit 55 performs irradiation field recognition for discriminating the irradiation field inside area and the irradiation field outside area.

In the irradiation field recognition, for example, Japanese Patent Application Laid-Open No. 63-25 / 1988
For example, as shown in FIG. 5A, a differentiation process is performed using image data on a line segment from a predetermined position P on the imaging surface toward the end of the imaging surface, using a method described in No. 9538. The differential signal Sd obtained by this differential processing is
As shown in FIG. 5B, since the signal level increases at the irradiation field edge, one signal field edge candidate point EP1 is obtained by determining the signal level of the differential signal Sd. A plurality of irradiation field edge candidate points EP1 to EPk are obtained by radially performing the process of obtaining the irradiation field edge candidate points around a predetermined position on the imaging surface. The irradiation field edge portion is obtained by connecting the edge candidate points adjacent to the plurality of irradiation field edge candidate points EP1 to EPk thus obtained by a straight line or a curve.

Further, a method disclosed in JP-A-5-7579 can be used. According to this method, when the imaging surface is divided into a plurality of small regions, in a small region outside the irradiation field where the irradiation of the radiation is blocked by the irradiation field diaphragm, the radiation dose of the radiation becomes substantially uniform, and the variance of the image data is reduced. Becomes smaller. Also, in a small area inside the irradiation field, the radiation amount is modulated by the subject, so that the variance value is higher than in the outside of the irradiation field. Further, in a small region including the irradiation field edge portion, the portion having the smallest radiation dose and the portion of the radiation dose modulated by the subject are mixed, so that the variance value is the highest.
From this, the small area including the irradiation field edge is determined based on the variance value.

Further, a method disclosed in JP-A-7-181609 can be used. In this method, the image data is rotated and moved with respect to a predetermined center of rotation, and rotated by the parallel state detection means until the boundary line of the irradiation field is parallel to the coordinate axis of the rectangular coordinates set on the image. When the state is detected, the straight-line equation calculating means calculates the straight-line equation of the boundary before rotation based on the rotation angle and the distance from the rotation center to the boundary. After that, the area of the irradiation field can be determined by determining the area surrounded by the plurality of boundary lines from the linear equation. If the irradiation field edge is a curve, the boundary point extracting means extracts, for example, one boundary point based on the image data, and extracts the next boundary point from a group of boundary candidate points around the boundary point. Similarly, by sequentially extracting the boundary points from the boundary candidate point group around the boundary point, it is possible to determine even if the irradiation field edge portion is a curve.

Here, the cassette type radiation image reader 2
0 and the conversion plate 62 are stored in the cassette stacker 61, the radiation image reader 2
Depending on the direction of 0, the direction of the conversion plate 62 stored in the cassette stacker 61, and the like, the direction of the image may not be constant. For example, the orientation of the radiation image reader 20 is changed according to the subject 5, or the conversion plate 62 is stored in the cassette stacker 61 in a different direction from that at the time of capturing a radiation image when generating the image data DT. In some cases, the orientation of the image is not constant. Therefore, the image processing unit 5
In 5, after the irradiation field recognition is performed, the orientation of the image is determined.

In the determination of the orientation of the image, the number of direction determination regions equal to or greater than the number of direction determination directions is set so as not to overlap each other in the irradiation field region, and the direction is determined for each of the direction determination regions. The determination representative value is calculated, and the direction is determined using the direction determination representative value. Here, in order to determine whether the orientation of the image is correct or whether the image is rotated at any angle of 90 °, 180 °, or 270 °, four direction determinations are performed because the number of determination directions is “4”. Set the area for
A direction discrimination representative value is calculated for each direction discrimination area, and the direction discrimination is performed using the direction discrimination representative value.

FIG. 6 shows a direction discriminating area.
In A to 6D, for example, four direction discriminating areas Ard-1 to Ard close to different sides of the substantially rectangular irradiation field area Ara
rd-4 is set. Here, FIG. 6A shows that the irradiation field area Ara is equally divided into three in the vertical and horizontal directions to provide nine areas, and the four areas excluding the four corners and the center are divided into direction discriminating areas Ard-1 to Ard-. 4 FIG. 6B shows a case where the central region shown in FIG. 6A is enlarged. Further, in FIGS. 6A and 6B, the corner of one direction discriminating area is in contact with the two direction discriminating areas, but they are provided apart as shown in FIG. 6C. Also, as shown in FIG. 6D, the irradiation field area can be divided into four using diagonal lines and set as direction discriminating areas Ard-1 to Ard-4.

The setting of the direction discriminating areas as shown in FIGS. 6A and 6D can be used for discriminating the directions of the photographed images of all parts such as the chest, abdomen, and pelvis. This is suitable for determining the orientation of a captured image. This is because the information near the center of the image is also used, so that the signal difference between the lung field and the mediastinum can be used effectively. The setting of the direction discriminating area as shown in FIG. 6B and FIG. 6C is suitable for discriminating the direction of a captured image of a part that does not include a lung field, such as the abdomen and the pelvis. Further, FIG.
The setting of the direction discriminating area as shown in FIG. 6C is suitable for discriminating the orientation of a captured image of a subject with a small body (such as a child). This is because, as shown in FIGS. 6B and 6D, if the width of the direction discriminating area is wide, in a subject having a small body, all of the four direction discriminating areas include the area directly irradiated with radiation, and the signal difference. This is because there is a case where it becomes difficult to obtain the image.

By the way, when the direction discrimination area is set as shown in FIGS. 6A to 6D, not only discrimination in four directions but also discrimination in two directions is possible. Alternatively, when there are only two types of rotation by 90 °, two directions can be determined by setting two direction determination areas as shown in FIGS. 6E and 6F.

FIG. 6E uses two adjacent direction discriminating areas, for example, the direction discriminating areas Ard-3 and Ard-4 from the four direction discriminating areas in FIG. 6A, and FIG. It uses two adjacent direction discriminating areas, for example, direction discriminating areas Ard-3 and Ard-4 from four 6D direction discriminating areas. When selecting two adjacent direction determination areas from the four direction determination areas, two direction determination areas are selected with high accuracy by selecting two direction determination areas according to the imaging region and the rotation direction of the radiation image. The direction can be determined.

Next, a direction discrimination representative value is calculated for each of the set direction discrimination areas. As the direction determination representative value, an average value or a maximum value of image data in the direction determination area, or a signal value at which a cumulative histogram has a predetermined ratio, for example, 50% or 99% is used. Here, by calculating the direction discrimination representative value using the cumulative histogram, even if the direction discrimination area includes some pixels whose signal levels are greatly separated from each other, the influence of these pixels can be reduced. In addition, for example, a representative value that better reflects a main structure in the direction determination area can be used as compared with a case where an average value is used.

When the direction discrimination representative value is calculated for each direction discrimination area in this manner, the anatomy of this photographed part is determined based on the direction discrimination representative value and the photographed part information input from the input device 54 or the like. The orientation of the image is determined based on the features of the geometric structure. Here, as a feature of the anatomical structure, the signal level of the image signal is low in the central part of the trunk passing through the spine because the radiation absorption amount is the largest. Further, since the body side has a small body thickness, the radiation absorption amount is small and the signal level of the image signal is high. further,
The region where the body part is imaged may include a part directly irradiated with radiation, and the signal level of the image signal is further increased in such a part. The signal level of the image signal of the imaging region is symmetric with respect to the spine, for example.

For this reason, for example, in order to determine the four directions with respect to the photographed image, the direction determination areas Ard-1, Ard-2, Ad
rd-3 and Ard-4 are set, and the direction discriminating areas Ard-1 and Ard-4 are set.
Direction determination representative values V1, V2, V of rd-2, Ard-3, Ard-4
3, V4 are obtained, and the direction determination representative values V1, V2, V3, V
4 and direction identification representative values V1, V2, V3, V based on the anatomical structure features based on the input imaging region information.
The direction can be determined from the magnitude relation of No. 4.

FIG. 7 shows a photographed part and a direction discrimination representative value V1,
It is a figure which shows the relationship of V2, V3, and V4. FIG. 7 shows a case where the direction discriminating area is set as shown in FIG. 6A. Here, when the front of the chest is photographed as shown in FIG. 7A, the spine is included in the regions Ard-1 and Ard-3,
Regions Ard-2 and Ard-4 contain many lung fields,
In most cases, since the linear radiation irradiation area on the body side is included, the direction determination representative values V1 and V3 are smaller than the direction determination representative values V2 and V4. Further, since the lung area is included in the region Ard-1 and the lung field is hardly included in the region Ard-3, the representative direction determination value V1 is
It becomes a value larger than 3 and has the relationship shown in FIG. 7B.

For this reason, when the direction determination representative value V3 is the minimum value among the direction determination representative values V1 to V4, it is determined that the orientation of the image is correct. Also, the direction determination representative value V1
Is the minimum, the image is 180 ° or -180.
° The direction is determined to be rotated. Similarly, if the direction determination representative value V2 is the minimum value, the image is determined to be in the direction rotated by 270 ° or −90 °, and if the direction determination representative value V4 is the minimum value, the image is 9 pixels.
It is determined that the rotation is 0 ° or -270 °.

When the front of the abdomen is photographed as shown in FIG. 7C, the vertebra is included in the regions Ard-1 and Ard-3, and the region Ard-
In 2, Ard-4, since a large number of digestive organs and the like are included, the direction determination representative values V1 and V3 are smaller than the direction determination representative values V2 and V4. In addition, since the pelvis is included in the region Ard-3, the direction determination representative value V3 is
It becomes a value smaller than 1 and has the relationship shown in FIG. 7D.

Therefore, as in the case where the front of the chest is photographed, the orientation of the image is determined to be correct when the representative value V3 is the minimum value, and when the representative value V1 is the minimum value. The image is determined to be rotated by 180 ° or −180 °, and when the direction determination representative value V2 is the minimum value, the image is determined to be rotated by 270 ° or −90 °, and the direction is determined. When the representative value V4 is the minimum value, it is determined that the image is rotated by 90 degrees or -270 degrees.

When the pelvis or the front of the hip joint is photographed as shown in FIG. 7E, the region Ard-1 includes the spine, and the regions Ard-2 and Ard-4 include the pelvis having a relatively thick bone. Since the region Ard-3 includes a pubic bone having a thin bone and a portion directly irradiated with radiation at the same time as the crotch region, the representative direction determination value has the relationship shown in FIG. 7F.

For this reason, in the same manner as described above, it is determined which of the direction determination representative values V1, V2, V3, and V4 is the minimum value, thereby determining how the image is rotated. can do.

In the above-described case, the four directions are determined using the imaged part information and the representative direction determination values V1, V2, V3, and V4.
It is also possible to make a determination in two directions using V3 and V4.

For example, a direction discriminating representative value having a small value is discriminated from the direction discriminating representative values V2 and V4 to obtain a direction discriminating representative value Va, and a direction discriminating representative value having a small value is discriminated from the direction discriminating representative values V1 and V3. As the direction determination representative value Vb,
When the value obtained by subtracting the representative direction determination value Vb from the representative direction determination value Va is equal to or greater than “0”, it is determined that the orientation of the image is correct. If the value obtained by subtracting the representative direction determination value Vb from the representative direction determination value Va is less than “0”, the image is determined to be rotated 90 °.

Further, discrimination in two directions can be performed by utilizing the symmetry of the photographed image. For example, the direction discrimination representative value V3 is calculated from the absolute value Wa of the subtraction value obtained by subtracting the direction discrimination representative value V3 from the direction discrimination representative value V1 and the direction discrimination representative value V2.
The absolute value Wb of the subtraction value obtained by subtracting 4 is obtained, and if the value obtained by subtracting the absolute value Wb from the absolute value Wa is “0” or more, the orientation of the image is determined to be correct. If the value obtained by subtracting the absolute value Wb from the absolute value Wa is less than “0”, it is determined that the image is rotated 90 °.

In the determination of the orientation of the image, the orientation of the image may be determined by a plurality of methods, and the final orientation may be determined based on the determination results. For example, direction determination is performed a plurality of times using an average value or a maximum value as a direction determination representative value, a value at which the cumulative histogram is 50% or 99%, and the final direction is determined from a plurality of determination results. It may be. For example, in the two-direction determination, the direction determination result based on the magnitude relationship between the above-described direction determination representative value Va and the direction determination representative value Vb, and the direction determination result based on the magnitude relationship between the absolute value Wa and the absolute value Wb are obtained. The final orientation may be determined.

When the orientation of the image is determined in this way, a process for setting the orientation of the image to the correct orientation is performed based on the determination result. Here, when it is determined that the image is not in the correct orientation, for example, the image is 180 ° or −180.
If it is determined that the image has been rotated by an angle, a process of rotating the image by 180 ° is performed. The image is 27
When it is determined that the image is rotated by 0 ° or −90 °, a process of rotating the image by 90 ° or −270 ° is performed. In addition, the image is 90 ° or -2.
When it is determined that the image is rotated by 70 °, a process of rotating the image by 270 ° or −90 ° is performed. For this reason, when FIG. 8A is in the correct orientation of the image, even if the image is rolled over as shown in FIG. 8B to FIG. 8D, a process of rotating the image is performed, and the process shown in FIG. 8B to FIG. Image data in the direction of the image shown in FIG. 8A is generated from the image data of the image.

Next, when the image data with the correct orientation of the image is generated, the level distribution of the image data is determined at the time of performing a normalization process for converting the distribution of the image data into a distribution of a desired level. Area (hereinafter referred to as “region of interest”)
Is set. By determining a representative value from the image data in the region of interest and converting the representative value to a desired level, image data of a desired level can be obtained.

The region of interest is not limited to the case where the region of interest is equal to the region within the irradiation field. For example, since it is common to perform imaging with the most important part in performing a diagnosis as the center of the irradiation field, a region such as a circle or rectangle is set at the center of the irradiation field region and the region of interest is set as You may do it. Here, in the area such as a circle or a rectangle, the diameter of the circle or the length of one side of the rectangle is set as, for example, “１ ／ to“ １ ／ ”of the long side or the short side of the irradiation field or the diagonal line.

Further, a region of interest corresponding to a predetermined human body structure may be set in the region within the irradiation field. For example, Japanese Unexamined Patent Publication
As described in Japanese Patent No. 218578, projections in the vertical direction and the horizontal direction (cumulative values in one direction of image data) are obtained, and an anatomical region determining unit determines an area of a lung field portion from the data. The determined area is set as a region of interest. As disclosed in JP-A-5-7578, the image data of each pixel is compared with a threshold, and an identification code is added to each pixel based on the comparison result. A region is determined by performing labeling for each group of consecutive pixels, and the determined region is set as a region of interest.

Next, representative values D1 and D2 are set from the image data in the set region of interest, and a process of converting the representative values to desired levels S1 and S2 is performed. Or,
A region for setting a representative value (hereinafter referred to as a “signal region”) is extracted from the region of interest, and representative values D1 and D2 are set from the image data in the extracted signal region.

The extraction of this signal area is described in
No. 62141 can be used. In this method, a histogram of image data is divided into a plurality of small areas by an automatic threshold selection method using a discrimination criterion method or the like, and a desired image portion among the divided small areas is extracted as a signal area.

Here, the setting of the region of interest and the extraction of the signal region can be performed by using the imaging region information when setting the region of interest and extracting the signal region.

In setting the representative values D1 and D2, for example, a substantially minimum value and a substantially maximum value in a region of interest or an extracted signal region are used as representative values. Also, a signal value such that the cumulative histogram in the signal area becomes a predetermined value, for example, 20% and 80% is used as a representative signal value. In addition, a signal value in which the cumulative histogram in the signal area is 60% with one representative value used, for example, is used as the representative signal value. Representative value D
In the setting of 1 and D2, by using the image data in the signal area, it is possible to perform a normalization process more suitable for the subject than in the case of using the image data in the area of interest.

When the representative values D1 and D2 are set in this manner, the representative values D1 and D2 are set to the desired reference value S1 as shown in FIG. , S2 are normalized. Here, the characteristic curve CC indicates the level of a signal output according to the radiation dose of the radiation applied to the imaging panel 21. Further, the normalization processing lookup table is generated by an operation using an inverse function of the function indicating the characteristic curve CC of the imaging panel 21. It is needless to say that the normalization processing may be performed by arithmetic processing without using the normalization processing lookup table.

As a result of this normalization processing, as shown in FIG. 10, the radiation doses Ra to Ra are lower than the doses R1 to R2 at which the radiation can obtain image data of the desired reference values S1 to S2.
Even with Rb, the image data of the desired reference values S1 to S2 can be obtained, so that the exposure of the subject can be reduced.

Next, gradation processing is performed using the normalized image data DTreg obtained by the normalization processing. FIG.
Reference numeral 1 denotes a gradation conversion characteristic. In the gradation processing, a gradation conversion curve shown in FIG.
Are the parameter value levels S1 ', S2'
The normalized image data DTreg is converted into output image data DTout such that The levels S1 'and S2' correspond to predetermined luminance or photographic density in the output image.

The gradation conversion curve is represented by the normalized image data DTre.
It is preferably a continuous function over the entire signal region of g, and its differential function is also preferably continuous.
Further, it is preferable that the sign of the differential coefficient is constant over the entire signal region.

Further, since the preferred shape of the gradation conversion curve and the levels S1 'and S2' differ depending on the photographing site, photographing position, photographing condition, photographing method, etc., the gradation transformation curve is created for each image. Or, for example,
As shown in No. 138, a plurality of basic tone conversion curves are stored in advance, and one of the basic tone conversion curves is read out and rotated and translated to obtain a desired tone conversion curve. Can be easily obtained. In addition,
The image processing unit 55 is provided with a gradation processing look-up table corresponding to a plurality of basic gradation curves. The image processing unit 55 obtains image data obtained by referring to the gradation processing lookup table based on the normalized image data DTreg. Is corrected in accordance with the rotation and parallel movement of the basic gradation conversion curve, so that output image data DTout subjected to gradation conversion can be obtained. In the gradation conversion process, two reference values S1, S2
, A single reference value or three or more reference values may be used.

Here, the selection of the basic gradation curve and the rotation and translation of the basic gradation curve are performed based on the photographing part, photographing conditions, photographing method and the like. The information is input to the input device 5
4, the basic gradation curve can be easily selected by using this management information, and the amount of rotation of the basic gradation curve and the moving amount of the parallel movement can be selected. Can be determined. Further, the levels of the reference values S1 and S2 may be changed based on an imaging part, an imaging position, an imaging condition, and an imaging method.

Further, the selection of the basic gradation curve and the rotation or translation of the basic gradation curve may be performed based on information on the type of image display device and the type of external device for image output. This is because the preferable gradation may differ depending on the image output method.

Next, the frequency emphasis processing and the dynamic range compression processing will be described. In the frequency emphasizing process, for example, in order to control the sharpness by the non-sharp mask process shown in Expression (1), the function F is calculated as follows.
3 and JP-B-62-62376. Soua = Sorg + F (Sorg−Sus) (1) where Soua is image data after processing, Sorg is image data before frequency enhancement processing, and Sus is image data before frequency enhancement processing. This is the unsharp data obtained by.

In this frequency emphasis processing, for example, F (Sor
g−Sus) is set to β × (Sorg−Sus), and β (emphasis coefficient) is changed substantially linearly between the reference values T1 and T2 as shown in FIG. As shown by the solid line in FIG. 13, when the values “A” and “B” are set to emphasize low luminance, β from the reference value S1 to the value “A” is maximized, and the value “ B "to the reference value T2. Also, the value "A" ~
Up to the value “B”, β is changed almost linearly. When the high luminance is emphasized, as shown by the broken line, β from the reference value T1 to the value “A” is minimized, and the value “B” to the reference value T2.
Up to the maximum. Further, from the value “A” to the value “B”, β
Is changed almost linearly. It should be noted that although not shown, β of the value “A” to the value “B” is maximized when the medium luminance is emphasized. Thus, in the frequency emphasis processing, the sharpness of an arbitrary luminance portion can be controlled by the function F.

Here, the reference values T1, T2 and the value "A",
“B” is obtained by a method similar to the method of determining the representative values D1 and D2 in the above-described setting of the gradation processing conditions.

The method of the frequency emphasis processing is not limited to the above unsharp mask processing.
For example, a technique such as the multi-resolution method disclosed in Japanese Patent No. 645 may be used. In the frequency emphasizing process, the frequency band to be emphasized and the degree of emphasis are set based on the photographing site, photographing position, photographing condition, photographing method, and the like, similarly to the selection of the basic gradation curve in the gradation process. .

In the dynamic range compression processing, a function G is determined by a method disclosed in Japanese Patent Publication No. 266318 in order to perform control such that the density is within a legible range by the compression processing shown in equation (2). Stb = Sorg + G (Sus) (2) where Stb is image data after processing, Sorg is image data before dynamic range compression processing, and Sus is image data before dynamic range compression processing by averaging processing or the like. Unsharp data.

Here, as shown in FIG. 14A, if the non-sharp data Sus has such a characteristic that G (Sus) increases when the level of the non-sharp data Sus becomes smaller than the level “La”, the density of the low-density area is reduced. Is high, and the image data Sorg shown in FIG. 14B is image data Stb in which the dynamic range on the low density side is compressed as shown in FIG. 14C.
Also, as shown in FIG. 14D, G (Sus) becomes G (Sus) when the non-sharp data Sus becomes smaller than the level “Lb”.
Is reduced, the density of the high-density area is determined to be high, and the image data S shown in FIG.
For org, the dynamic range on the high density side is compressed as shown in FIG. 14E. Here, the levels “La” and “Lb”
Are the representative values D1,
It is obtained by a method similar to the method of determining D2. In addition,
Dynamic range compression processing also includes
A correction frequency band and a degree of correction are set based on a shooting condition, a shooting method, and the like.

In the image processing apparatus of the present invention, when performing the above-described irradiation field recognition processing and image direction determination, or when determining image processing conditions such as gradation processing, frequency processing, and dynamic range compression processing, diagnosis is performed. It is not necessary to execute the processing by using the entire information amount of the image data of the radiation image to be processed. For example, by using the image data of the reduced image obtained by performing the pixel thinning processing, the processing speed is improved. Further, it is preferable because the amount of memory used can be reduced.

The image data obtained by performing image processing in the image processing unit 55 is subjected to rotation processing based on the determination result of the image direction, and stored in the frame memory 51, the disk device 53, or the storage device 93. Is done. Further, the image data obtained by performing the image processing in the image processing unit 55 may be stored together with the direction determination flag indicating the determination result of the image direction without changing the image direction.

The image data output to the external device 100 or the like via the output interface 48 or the interface unit 95 may be image data after image processing.
It is preferable to output the image data before image processing in association with the direction determination flag, the image processing conditions obtained by the image processing unit 55, and the like. This is because the image data before image processing can be obtained by processing the image data before image processing using the direction determination flag, the image processing conditions, and the like by the external device 100 and the like, and the image processing conditions and the like can be obtained. This is because new image data can be obtained by changing and processing the image data before image processing.

Although the image processing unit 55 automatically determines the direction of the image, the input unit 54 and the operation unit 91
Is operated to correct the determination result of the image direction in the image processing unit 55, the image direction is forcibly set to the predetermined direction regardless of the determination result of the image direction, and the subsequent processing is performed. It can also be done. It should be noted that, by making the determination result of the orientation of the image correctable, even if the orientation of the image is erroneously determined, the orientation of the image can of course be corrected.

As described above, according to the above-described embodiment, even if the orientation of the image is turned over or the like, it is possible to determine the orientation of the image and determine the correct orientation. Further, the present invention can be applied to photographed images of various kinds of photographed parts. Further, since the orientation of the image is determined using the image data in the irradiation field recognized by the irradiation field recognition, a highly accurate determination result can be obtained. Further, since the orientation of the image is determined using the representative value based on the cumulative histogram, the determination accuracy can be improved.

[0111]

According to the present invention, an irradiation field region is recognized using image data of a radiation image, and a plurality of direction discrimination regions are set in the recognized irradiation field region. The direction of the radiation image is determined using the direction determination representative value of the image data in the area, and image processing of the radiation image is performed using the determination result and the image data. For this reason, the direction of the radiation image can be determined even if the image is turned over or reversed, and image processing of the radiation image can be performed correctly.

The direction discrimination representative value is set based on the cumulative histogram of the image data in the direction discrimination area. For this reason, the influence of the pixels in the direction determination area where the image data levels are far apart can be reduced, and the direction of the image can be correctly determined.

Further, since the determination result of the orientation of the radiation image, the image processing condition, and the image data before image processing are output in association with each other, new image processing can be performed using these.

Further, since the determination result of the direction of the radiation image can be corrected by the image direction correction information, the image processing can be performed by forcibly changing the direction of the image to a desired direction.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a radiation image capturing system.

FIG. 2 is a diagram illustrating a configuration of a radiation image reader using an FPD.

FIG. 3 is a diagram showing a configuration of a controller.

FIG. 4 is a diagram showing a configuration when a stimulable fluorescence detector is used.

FIG. 5 is a diagram for explaining irradiation field recognition processing.

FIG. 6 is a diagram showing a direction discrimination area.

FIG. 7 is a diagram illustrating a relationship between an imaging region and a direction determination representative value.

FIG. 8 is a diagram for explaining rotation of the direction of an image.

FIG. 9 is a diagram for explaining level conversion.

FIG. 10 is a diagram showing a normalization process.

FIG. 11 is a diagram showing gradation conversion characteristics.

FIG. 12 is a diagram illustrating a relationship between an enhancement coefficient and image data.

FIG. 13 is a diagram illustrating a relationship between an enhancement coefficient and image data.

FIG. 14 is a diagram illustrating a dynamic range compression process.

FIG. 15 is a diagram showing the orientation of a subject.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Radiation generator 20, 60 Radiation image reader 21 Imaging panel 24 Scan drive circuit 26 Image data generation circuit 28 Reading control circuit 29 Memory 40 Controller 41 CPU (Central Processing Unit) 45 Display control unit 46 Frame memory control unit 47 Input interface 48 output interface 49 data read control unit 50 disk control unit 51 frame memory 52 image display device 53 disk device 54 input device 55 image processing unit 61 cassette stacker unit 62 conversion plate 63 cassette 64 stacker drive control unit 65 stacker drive unit 66 plate transport Control unit 67 Plate transport unit 68 Erasing unit 70 Light beam generating unit 71 Scanning unit 72 Reflecting mirror 73 Condenser 74 Filter 75 Photomultiplier 76 Current / voltage converter 77 Amplifying unit 78 Replacement unit 80 Read control unit 81 High voltage power supply for photomultiplier 90 Main CPU (Central Processing Unit) 91 Operation unit 92 Image processing unit 93 Storage device 94 Image display device 95 Interface unit 96 Host computer 97 Diagnosis device 98 Patient registration terminal 100 External machine

Claims (9)

[Claims] 1. An image processing apparatus for performing image processing of a radiation image using image data of a radiation image generated based on radiation transmitted through a subject, comprising: an irradiation field recognizing means for recognizing an irradiation field area of the radiation; An area setting means for setting a plurality of direction discriminating areas that do not overlap each other in the recognized irradiation field area; and for each of the set direction discriminating areas, a direction discriminating representative of image data in the direction discriminating area. Representative value determining means for determining a value, image direction determining means for performing a predetermined calculation using the determined plurality of direction determination representative values, and determining an image direction of the radiation image based on the calculation result; and Image data processing means for determining an image processing condition based on the determination result in the direction determining means and the image data and performing image processing on the radiation image. The image processing apparatus according to claim. 2. The image processing apparatus according to claim 1, wherein the area setting unit sets the plurality of direction determination areas according to the number of directions for determining the direction of the radiation image. 3. The irradiation field recognizing means recognizes a substantially rectangular irradiation field area, and the area setting means recognizes the plurality of direction discriminating areas by a substantially rectangular irradiation field recognized by the irradiation field recognizing means. 3. The image processing apparatus according to claim 1, wherein the image processing apparatus is set close to different sides of the region. 4. The apparatus according to claim 1, wherein said representative value determining means determines a direction determination representative value based on a cumulative histogram of image data in the set direction determination area. An image processing apparatus according to claim 1. 5. The image processing apparatus according to claim 1, wherein the image data processing unit performs a process including a gradation process as image processing of the radiation image. 6. The image processing apparatus according to claim 1, further comprising an image display unit that displays a radiation image using image data that has been subjected to image processing by the image data processing unit. Image processing device. 7. An image processing apparatus comprising: an output unit configured to output a determination result of the image direction determination unit and an image processing condition determined by the image data processing unit to an external device in association with image data of the radiation image. The image processing apparatus according to claim 1. 8. An imaging direction information input means for inputting imaging part information of the radiographic image, and a determination of an image direction by the image direction determining means based on the imaging part information input by the imaging part information input means. 8. The image processing apparatus according to claim 1, wherein image processing conditions are determined by said image data processing means. And a correction information input unit for inputting image direction correction information, wherein the image direction determination unit corrects an image direction determination result based on the image direction correction information input by the correction information input unit. The image processing apparatus according to claim 1, wherein the image processing is performed.