JP3800892B2 - Radiation image processing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radiographic image processing apparatus that processes a radiographic image, and can automatically determine the quality of an input image, a selected process, and a set region of interest, and has been obtained from a system or apparatus. The present invention relates to a radiation image processing apparatus capable of changing processing contents based on information.
[0002]
[Prior art]
Radiation images such as X-ray images are often used for disease diagnosis, etc. In order to obtain this X-ray image, X-rays transmitted through the subject are irradiated onto a phosphor layer (phosphor screen), thereby Conventionally, so-called radiographs, in which visible light is generated and developed by irradiating a film using a silver salt with the visible light in the same manner as ordinary photographs, have been used.
[0003]
However, in recent years, a method for taking out an image directly from a phosphor layer without using a film coated with silver salt has been devised. In this method, the radiation that has passed through the subject is absorbed by the phosphor, and then the phosphor is excited by light or thermal energy, for example, so that the radiation energy accumulated by the phosphor is absorbed as fluorescence. There is a method of obtaining an image signal by radiating and photoelectrically converting the fluorescence.
[0004]
Specifically, for example, US Pat. No. 3,859,527 and JP-A-55-12144 disclose a radiation image conversion method using a stimulable phosphor and using visible light or infrared light as stimulating light. This method uses a radiation image conversion panel in which a photostimulable phosphor layer is formed on a support. The radiation transmitted through the subject is applied to the photostimulable phosphor layer of the conversion panel, and the radiation of each part of the subject is detected. Radiation energy corresponding to the transmittance is accumulated to form a latent image, and then the stimulated layer is scanned with stimulated excitation light to radiate the accumulated radiation energy and convert it into light. This optical signal is photoelectrically converted to obtain a radiation image signal.
[0005]
The radiographic image signal thus obtained is subjected to image processing as it is or output to a silver salt film, CRT or the like for visualization or filing in an electronic filing device. In the image processing, the density of the region of interest in the reconstructed image (the region including the image part necessary for medical diagnosis) is made constant, and the shadow of the human body structure and lesion (region of interest) is output more easily. For this purpose, image processing such as gradation processing and spatial frequency processing is performed.
[0006]
For example, in the radiation image processing apparatus disclosed in Japanese Patent Application Laid-Open No. 3-218578, the region of interest is determined by analyzing the image signal, and the gradation processing condition is automatically determined based on the image signal in the region of interest. Thus, it is disclosed that gradation processing is performed, whereby an output image having a stable density and gradation can be automatically obtained and diagnostic performance can be improved.
[0007]
By the way, in the radiograph, the radiographer (radiologist) adjusts the irradiation dose, tube voltage, etc. according to the patient's body shape, the part to be observed, etc. based on the know-how obtained from experience, and the output image is the radiographer's According to the adjustment result, it is reproduced as it is. However, there is a possibility that imaging may fail due to the peculiarity of the patient's body shape or imaging errors, etc., and the radiographs visualized by the development process are visually judged to determine the quality of the imaging, and re-imaging etc. according to the determination result I was dealing with.
[0008]
In this regard, in the case of a system that obtains a radiographic image signal using the radiation image conversion panel, since development processing is unnecessary, it is possible to immediately determine whether or not radiography is good (imaging conditions or / and reading conditions are poor) on the spot. In addition, since image processing is performed after image capturing and reading as an image signal, it is possible to obtain a desired image by compensating image capturing and reading conditions to some extent by image processing.
[0009]
In addition, since the radiation image information is handled as the image signal in the system for obtaining the irradiation line image signal as described above, it is possible to automate the determination of the quality of the input image and processing.
[0010]
As such a quality determination, for example, there is one described in Japanese Patent Application Laid-Open No. 6-78910, and there is known a method for determining the quality of image data subjected to image processing.
[0011]
[Problems to be solved by the invention]
However, since the quality is determined using the processed image, there is a problem that the determination is made after all the processes are completed. In addition, since only the information in the image is referred to, there is a problem that there is little information that can be used for determination conditions and processing conditions.
[0012]
The present invention has been made in view of the problems as described above, and performs processing in consideration of information obtained from the apparatus / system, can perform processing more suitable for diagnosis, and fails in input or processing. An object of the present invention is to realize a radiographic image processing apparatus capable of determining the above in each process and performing rapid processing.
[0013]
It is another object of the present invention to realize a radiographic image processing apparatus capable of providing a smooth flow to reprocessing by omitting time by detecting a failure at the input or processing stage.
[0014]
[Means for Solving the Problems]
The present invention for solving the above problems is as follows.
(1) The first invention (Claim 1) is an image area for determining image processing conditions by analyzing image data of a radiographic image formed corresponding to the amount of radiation transmitted through each part of a subject. Area setting means for setting the image processing condition setting means for determining image processing conditions based on the statistical properties of the image data in the image area set by the area setting means, and the area setting means The radiation image processing apparatus is characterized by comprising image region position quality determination means for determining the quality of the image area position and outputting an image area position quality determination signal.
[0015]
In the present invention, when setting an image region for determining image processing conditions by analyzing image data of a radiographic image formed corresponding to the amount of transmitted radiation passing through each part of the subject, the set image is set. The image processing conditions are determined based on the statistical properties of the image data in the area, and the quality of the set image area position is determined, so the appropriate image processing condition is determined at the appropriate image area position. Will be able to. For this reason, a radiographic image more suitable for diagnosis can be obtained.
[0016]
The image area position quality determination means preferably determines the quality of the image area position based on the statistical properties of the image data in the image area set by the area setting means.
[0017]
The image area position quality determination means preferably determines the quality of the image area position by using position information in the entire image of the image area set by the area setting means.
[0018]
The image area position pass / fail determination means includes, as data indicating the statistical properties in the image area set by the area setting means, a substantially maximum value, a substantially minimum value of the image data, and a parameter indicating the degree of dispersion. , Based on at least one of a ratio of the image data distributed within the predetermined range, a parameter indicating the degree of dispersion of the image data within the predetermined range, and a parameter indicating the degree of separation by the discriminant analysis method of the image data, It is desirable to determine the quality of the image area position.
[0019]
The image area position pass / fail determination means includes a specific area setting means for setting a specific area in the image separately from the image area by the image area determination means, and the area setting means is used as position information in the entire image. It is desirable to determine whether the image area position is good or not based on whether or not the image area set by (1) includes the area set by the specific area setting means.
[0020]
The area set by the specific area setting means is preferably a predetermined area in the image.
It is desirable that the area set by the specific area setting means is at least one of a maximum signal value area or a minimum signal value area in the subject.
[0021]
Note that when the defect is determined based on the image area position pass / fail determination signal, the area setting means sets the data indicating the statistical properties in the image area in a direction approaching a desired value. It is desirable to provide area setting resetting means for resetting the area.
[0022]
The area set by the area setting unit is reset in a direction in which the position of the image area in the entire image approaches the desired position when a defect is determined based on the image area position pass / fail determination signal. It is desirable to provide an area setting resetting means.
[0023]
It is desirable to provide failure determination time processing means changing means for performing processing by another preset processing means when a defect is determined based on the image area position pass / fail determination signal.
[0024]
It is desirable to have an image area warning signal output means for outputting a signal when a defect is determined based on the image area position pass / fail determination signal.
The failure determination time processing means changing means is preferably default image area setting means for setting the image area to a preset area.
[0040]
DETAILED DESCRIPTION OF THE INVENTION
First, embodiments of the present invention will be described in detail with reference to the drawings. First, the configuration of the radiographic image processing apparatus according to the present embodiment will be described, then the operation of the radiographic image processing apparatus will be described, and further detailed description of image processing will be given.
[0041]
<Configuration of radiation image processing apparatus>
FIG. 2 is a system configuration diagram showing the overall configuration of the radiation image processing apparatus. The radiation generator 30 is controlled by the controller 10, and the radiation emitted from the radiation generator 30 is applied to the imaging panel mounted on the front surface of the radiation image reader 40 through the subject 5.
[0042]
FIG. 3 shows a configuration of a radiation image reader 40 using an FPD (Flat Panel Display). The imaging panel 41 has a substrate having a thickness sufficient to obtain a predetermined rigidity, and a detection element 412-(1,1) that outputs an electrical signal on the substrate according to the dose of irradiated radiation. ) To 412- (m, n) are two-dimensionally arranged in a matrix. Further, the scanning lines 415-1 to 415-m and the signal lines 416-1 to 416-n are disposed so as to be orthogonal, for example.
[0043]
The scanning lines 415-1 to 415-m of the imaging panel 41 are connected to the scanning driving unit 44. When the readout signal RS is supplied from the scan driver 44 to one of the scanning lines 415-1 to 415-m (p is any value of 1 to m), the scanning line 415 is supplied. Electric signals SV-1 to SV-n corresponding to the radiation dose irradiated from the detection element connected to -p are output to the image data generation circuit 46 via the signal lines 416-1 to 416-n. Supplied.
[0044]
This detection element 412 may be any element that outputs an electrical signal corresponding to the dose of irradiated radiation. For example, when a detection element is formed using a photoconductive layer in which electron-hole pairs are generated and change in resistance when irradiated with radiation, the detection element is in accordance with the amount of radiation generated in the photoconductive layer. A quantity 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 46 as an electrical signal. It is desirable that the photoconductive layer has a high dark resistance value, such as amorphous selenium, lead oxide, cadmium sulfide, mercuric iodide, or an organic material exhibiting photoconductivity (photoconductivity to which an X-ray absorption compound is added. In particular, amorphous selenium is desirable.
[0045]
When the detection element 412 is formed using, for example, a scintillator that generates fluorescence when irradiated with radiation, an image signal is generated by generating an electrical signal based on the fluorescence intensity generated by the scintillator with a photodiode. The circuit 46 may be supplied.
[0046]
As the imaging panel 41 using such a configuration, as disclosed in JP-A-9-90048, X-rays are absorbed by a phosphor layer such as an intensifying screen to generate fluorescence, and the intensity of the fluorescence. Is detected by a photodetector such as a photodiode provided for each pixel. As another fluorescence detecting means, there is a method using a CCD or a C-MOS sensor.
[0047]
In particular, in the imaging panel (FPD) of the method disclosed in the above Japanese Patent Laid-Open No. 6-342098, since the X-ray dose is directly converted into the charge amount for each pixel, the sharpness degradation in the FPD is small and the sharpness is excellent. Since an image is obtained, the effects of the X-ray image recording system and the X-ray image recording method are great and preferable.
[0048]
Furthermore, the imaging panel 41 can be configured as shown in FIGS. 17 and 18. FIG. 17 is a front view of a radiation image detector that can be used as the imaging panel 41, and shows an example in which the radiation image detector is constituted by a plurality of units. The dotted line in FIG. 17 is a line of the grid 50 of the radiation image detector, but is actually hidden from the protective member and the X-ray scintillator and cannot be seen from the front. FIG. 17 shows an example of 6 × 6 = 36 units, but the number is not limited to this.
[0049]
FIG. 18 is a schematic diagram of a longitudinal section of a radiation image detector. The radiation image detector is configured by arranging an X-ray scintillator 51, a lens array 52, and area sensors 54 corresponding to the lenses 53 of the lens array 52 in this order. The X-ray scintillator 51 is protected by a protection member 55. Each lens 53 of the lens array 52 is supported by a lens support member 58, and a transparent member 56 is disposed between the X-ray scintillator 51 and the lens array 52. The area sensor 54 is supported by an area sensor support member 57.
[0050]
The shape, thickness, ray path, etc. of the elements of the radiographic image feeding rod are not accurate. The grid 50 does not directly touch the X-ray scintillator 51 but abuts against the transparent member 56, thereby preventing the grid 50 from hitting the X-ray scintillator 51 and scratching it, and the boundary line of the grid 50 to Prevents missing parts.
[0051]
Since the area sensors 54 corresponding to the respective lenses 53 of the lens array 52 are arranged in this order, the spatial resolution is high, the image quality is high, the thickness is small, the size is small, and the weight is light.
[0052]
The X-ray scintillator 51 emits visible light upon exposure to X-rays such as gadolinium oxysulfide and cesium iodide, and the X-ray scintillator 51 emits visible light upon exposure to X-rays, resulting in high spatial resolution and high image quality. is there.
[0053]
The lens array 52 is formed from a lens group composed of a combination of two or more different lenses 53, has high spatial resolution, high image quality, and can be made thin. If the imaging magnification of the lens 53 is from 1 / 1.5 to 1/20, and the imaging magnification is greater than 1 / 1.5, the area sensor becomes too large to be disposed, and if it is less than 1/20, X The distance from the line scintillator 51 to the lens increases, and the thickness of the radiation image detector increases.
[0054]
A clear image can be obtained by using a solid-state imaging device such as a CCD or C-MOS sensor as the area sensor 54.
The image data generation circuit 46 sequentially selects the electrical signal SV supplied based on an output control signal SC from a read control circuit 48 described later, and converts it into digital image data DT. The image data DT is supplied to the reading control circuit 48.
[0055]
The reading control circuit 48 is connected to the controller 10 and generates a scanning control signal RC and an output control signal SC based on the control signal CTD supplied from the controller 10. The scanning control signal RC is supplied to the scanning drive unit 44, and the readout signal RS is supplied to the scanning lines 415-1 to 415-m based on the scanning control signal RC.
[0056]
The output control signal SC is supplied to the image data generation circuit 46. For example, when the imaging panel 41 is configured by (m × n) detection elements 412 as described above by the scanning control signal RC and the output control signal SC from the reading control circuit 48, the detection element 412− Assuming that data based on the electric signal SV from (1,1) to 412- (m, n) is data DP (1,1) to DP (m, n), data DP (1,1), DP (1 , 2),... DP (1, n), DP (2,1),..., DP (m, n) in this order, and the image data DT is generated by the image data generation circuit 46. To the reading control circuit 48. Further, the reading control circuit 48 also performs processing for sending the image data DT to the controller 10.
[0057]
Image data DT obtained by the radiation image reader 40 is supplied to the controller 10 via the reading control circuit 48. If the image data obtained by logarithmic conversion processing is supplied when the image data obtained by the radiation image reader 40 is supplied to the controller 10, the processing of the image data in the controller 10 can be simplified.
[0058]
Further, the radiation image reader is not limited to the one using FPD, and may be one using a stimulable phosphor. FIG. 4 shows a configuration when a radiation image reader 60 using a stimulable phosphor is used. In the conversion panel 61 irradiated with radiation, a stimulable phosphor layer is stimulated on the support. It is provided by vapor deposition of photosensitive phosphor or application of stimulable phosphor coating. This photostimulable phosphor layer is shielded or covered with a protective member in order to block adverse effects and damages caused by the environment.
[0059]
A light beam generating unit (gas laser, solid state laser, semiconductor laser, etc.) 62 generates a light beam whose emission intensity is controlled. This light beam reaches the scanning unit 63 via various optical systems, is deflected by the scanning unit 63, further deflects the optical path by the reflecting mirror 64, and is guided to the conversion panel 61 as the excitation excitation scanning light. .
[0060]
A condensing end made of an optical fiber or a sheet-like light guide member of the condensing body 65 is disposed in the vicinity of the conversion panel 61 where the excitation light is scanned, and scanning of the light beam from the light beam generating unit 62 is performed. Thus, the stimulated light emission having the light emission intensity proportional to the latent image energy generated in the conversion panel 61 is received.
[0061]
The filter 66 passes only light in the stimulated emission wavelength region from the light introduced from the light collector 65, and the light that has passed through the filter 66 is incident on the photomultiplier 67.
[0062]
The photomultiplier 67 generates a current signal corresponding to incident light by photoelectric conversion. This current signal is supplied to the current / voltage conversion unit 70 and converted into a voltage signal. Further, the voltage signal is amplified by the amplifying unit 71 and then converted to digital image data DT by the A / D converting unit 72. Here, a logarithmic conversion amplification unit (log amplifier) is used as the amplification unit 71. The image data DT is sequentially subjected to image processing in the image processing apparatus 80, and the image data DTC after image processing is transmitted to the printer 83 via the interface 82.
[0063]
A CPU (Central Processing Unit) 81 is for controlling image processing in the image processing device 80. In the image processing device 80, various image processing (for example, spatial frequency processing, dynamic range processing) is performed on the image data DT. Compression, gradation processing, enlargement / reduction processing, movement, rotation, statistical processing, etc.) to generate image data DTC in a form suitable for diagnosis.
[0064]
This image data DTC is supplied to the printer 83, and a hard copy of the radiation image of each part of the human body can be obtained from the printer 83. A monitor such as a CRT may be connected to the interface 82, and a storage device (filing system) that can store image data of a plurality of radiation images may be connected.
[0065]
The read controller 75 also adjusts the light beam intensity of the light beam generator 62, adjusts the gain of the photomultiplier 67 by adjusting the power supply voltage of the high voltage power supply 76 for the photomultiplier, and adjusts the current / voltage converter 70 and the amplifier 71. Gain adjustment and adjustment of the input dynamic range of the A / D converter 72 are performed, and the reading gain is adjusted comprehensively.
[0066]
The image data DT obtained from the A / D conversion unit 72 is supplied to the controller 10 and controls the operation of the reading control unit 75 by a control signal CTD from the controller 10.
[0067]
The radiation image reader may irradiate light from a light source such as a laser or a fluorescent lamp onto a silver salt film on which a radiation image is recorded, and photoelectrically convert the transmitted light of the silver salt film to generate image data. Good. Moreover, the structure which converts radiation energy directly into an electrical signal using a radiation quantum counting type detector, and produces | generates image data may be sufficient.
[0068]
Next, the configuration of the controller 10 is shown in FIG. The CPU 11 for controlling the operation of the controller 10 is connected to the system bus 12 and the image bus 13 and to the input interface 17. The operation of the CPU 11 for controlling the operation of the controller 10 is controlled based on a control program stored in the memory 14.
[0069]
A display control unit 15, a frame memory control unit 16, an output interface 18, a shooting control unit 19, a disk control unit 20, and the like are connected to the system bus 12 and the image bus 13. Is controlled, and image data is transferred between the units via the image bus 13.
[0070]
A frame memory 21 is connected to the frame memory control unit 16, and image data obtained by the radiation image reader 40 is stored via the imaging control unit 19 and the frame memory control unit 16. The image data stored in the frame memory 21 is read and supplied to the display control unit 15 and the disk control unit 20. The frame memory 21 may store the image data supplied from the radiation image reader 40 after being processed by the CPU 11.
[0071]
An image display device 22 is connected to the display control unit 15, and a radiographic image based on the image data supplied to the display control unit 15 is displayed on the screen of the image display device 22. Here, when the number of display pixels of the image display device 22 is smaller than the number of pixels of the radiation image reader 40, the entire captured image can be displayed on the screen by reading out the image data. Further, if image data in a region corresponding to the number of display pixels of the image display device 22 is read, a captured image at a desired position can be displayed in detail.
[0072]
When image data is supplied from the frame memory 21 to the disk control unit 20, for example, the image data is continuously read out and written into the FIFO memory in the disk control unit 20, and then sequentially recorded in the disk device 23. The
[0073]
Further, the image data read from the frame memory 21 and the image data read from the disk device 23 can be supplied to the external device 100 via the output interface 18.
[0074]
In the image processing unit 26, irradiation field recognition processing, region of interest setting, normalization processing and gradation processing of the image data DT supplied from the radiation image reader 40 via the imaging control unit 19, and image area position pass / fail determination Processing is performed. Further, frequency enhancement processing, dynamic range compression processing, or the like may be performed. In addition, image processing etc. can also be performed as the structure which CPU11 serves as the image processing part 26. FIG.
[0075]
Therefore, the image processing unit 26 includes an area setting unit for determining ROI in the claims, an image processing condition setting unit, an image area quality determination unit, an input image quality determination unit, an image processing unit quality determination unit, an image processing unit change unit, Is configured.
[0076]
An input device 27 such as a keyboard is connected to the input interface 17. By operating the input device 27, management information such as information for identifying image data obtained by photographing and information relating to photographing is input.
[0077]
As the external device 100 connected to the output interface 18, a scanning laser exposure apparatus called a laser imager is used. In this scanning laser exposure apparatus, the intensity of a laser beam is modulated by image data, and after exposure to a conventional silver halide photographic light-sensitive material or thermal phenomenon silver halide photographic light-sensitive material, an appropriate development process is performed, thereby performing radiographic image processing. A hard copy can be obtained.
[0078]
Although the image data supplied from the radiation image reader 40 is stored in the frame memory 21, the supplied image data may be stored after being processed by the CPU 11. The disk device 23 stores image data stored in the frame memory 21, that is, image data supplied from the radiation image reader 40 and image data obtained by processing the image data by the CPU 11 together with management information. be able to.
[0079]
<Operation of radiation image processing apparatus>
Next, the operation of the above radiation image processing apparatus will be described. When obtaining a radiographic image of the subject 5, the subject 5 is assumed to be positioned between the radiation generator 30 and the imaging panel 41 of the radiographic image reader 40, and the radiation emitted from the radiation generator 30 is the subject 5. And the radiation that has passed through the subject 5 enters the imaging panel 41. The same applies to the case where the radiation image reader 60 is used instead of the radiation image reader 40. In the following description, the radiation image reader 40 is used, and the description when the radiation image reader 60 is used is omitted. To do.
[0080]
Management information indicating identification of the subject 5 to be photographed and information relating to photographing is input to the controller 10 using the input device 27. Input of management information using the input device 27 is performed by operating a keyboard, using a magnetic card, a bar code, HIS (in-hospital information system: network-based information management), or the like.
[0081]
This management information includes, for example, an ID number, name, date of birth, sex, imaging date and time, imaging site and imaging position (for example, which part of the human body was irradiated with radiation from which direction), imaging method (simple imaging, contrast imaging) Imaging, tomographic imaging, magnified imaging, etc.), imaging conditions (tube voltage, tube current, irradiation time, presence / absence of use of scattered radiation removal grid, etc.).
[0082]
The shooting date and time can be automatically obtained from the CPU 11 by using a clock function built in the CPU 11. It should be noted that the management information to be input may be only related to the subject to be photographed at that time. A series of management information is input in advance, and the subjects are photographed in the order of input, or the management that has been input as necessary. Information may be read and used.
[0083]
When the power switch of the radiation image reader 40 is turned on, the imaging panel 41 is initialized by the reading control circuit 48 and the scanning drive unit 44 of the radiation image reader 40 based on the control signal CTD from the controller 10. Is called. This initialization is for obtaining a correct electrical signal corresponding to the radiation dose emitted from the imaging panel 41.
[0084]
When the initialization of the imaging panel 41 in the radiation image reader 40 is completed, the radiation from the radiation generator 30 can be irradiated. Here, when a switch for irradiating radiation is provided in the radiation generator 30, when this switch is operated, radiation is emitted from the radiation generator 30 toward the subject 5 for a predetermined time, and A signal DFS indicating the start of radiation irradiation and a signal DFE indicating the end of irradiation are supplied to the controller 10.
[0085]
At this time, the radiation amount of the radiation applied to the imaging panel 41 of the radiation image reader 40 is modulated by the subject 5 because the degree of radiation absorption by the subject 5 is different. In the detection elements 412-(1,1) to 412-(m, n) of the imaging panel 41, an electrical signal based on the radiation modulated by the subject 5 is generated.
[0086]
Next, in the controller 10, a predetermined time after the signal DFS is supplied, for example, when the irradiation time of the radiation is about 0.1 seconds, a time longer than this irradiation time (for example, about 1 second), or Immediately after the signal DFE is supplied, the control signal CTD is supplied to the reading control circuit 48 of the radiation image reader 40 in order to start generation of the image data DT by the radiation image reader 40.
[0087]
On the other hand, when a switch for irradiating radiation is provided in the controller 10, when this switch is operated, an irradiation start signal CST for starting irradiation of radiation is transmitted via the imaging control unit 19 to the radiation generator. 30, radiation is emitted from the radiation generator 30 toward the subject 5 for a predetermined time. This irradiation time is set based on management information, for example.
[0088]
Next, in the controller 10, a predetermined time after outputting the irradiation start signal CST, a control signal CTD for starting generation of image data by the radiation image reader 40 is sent to the reading control circuit 48 of the radiation image reader 40. Supply. The controller 10 supplies the radiographic image reader 40 with a control signal CTD for starting generation of image data by the radiographic image reader 40 after detecting the end of radiation irradiation by the radiation generator 30. It is good. In this case, generation of image data during radiation irradiation can be prevented.
[0089]
In the reading control circuit 48 of the radiation image reader 40, the scanning control signal RC and the output control signal SC are generated based on the control signal CTD for starting the generation of the image data supplied from the controller 10. The scanning control signal RC is supplied to the scanning drive unit 44 and the output control signal SC is supplied to the image data generation circuit 46, and the image data DT obtained from the image data generation circuit 46 is supplied to the reading control circuit 48. The The image data DT is sent to the controller 10 by the reading control circuit 48.
[0090]
The image data DT supplied to the controller 10 is stored in the frame memory 21 via the imaging control unit 19, the frame memory control unit 16, and the like. A radiographic image can be displayed on the image display device 22 by using the image data stored in the frame memory 21. Further, the image data stored in the frame memory 21 is processed by the image processing unit 26 and supplied to the display control unit 15, or the image data subjected to the image processing is stored in the frame memory 21, and the frame memory 21 By supplying the stored image data to the display control unit 15, 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 image data that has undergone image processing to the external device 100, a hard copy of a radiation image suitable for diagnosis or the like can be obtained.
[0091]
In the image processing unit 26, even if the level distribution of the image data output from the imaging panel 41 varies due to the difference in radiation dose, the normalization of the image data DT is always performed so that a stable radiation image can be obtained. Processing is performed. Even if the distribution of the level of the image data fluctuates, gradation processing is performed on the normalized image data DTreg, which is image data after normalization processing, in order to obtain a density and contrast radiation image suitable for diagnosis and the like. Done. Further, the image processing unit 26 reduces the contrast of the fine structure portion of the subject in the frequency enhancement processing for controlling the sharpness of the normalized radiation image with respect to the normalized image data DTreg and the entire radiation image having a wide dynamic range. It is also possible to perform a dynamic range compression process so that the density is within the easy-to-see density range.
[0092]
<Contents of image processing>
In the radiographic image processing apparatus according to the present embodiment, prior to the normalization processing, gradation processing, and dynamic range compression processing described above, irradiation field recognition processing, input image quality determination, processing key selection quality determination, ROI recognition, It is characterized by performing ROI pass / fail judgment.
[0093]
That is, the image processing procedure of the present embodiment is different from the conventional processing procedure and is as shown in FIG. As shown in FIG. 1, the processing procedure of this embodiment is as follows.
・ Irradiation field recognition processing,
・ Input image pass / fail judgment processing,
・ Process key selection pass / fail judgment processing,
・ ROI recognition processing,
・ ROI pass / fail judgment processing,
・ Dynamic range compression processing, frequency processing, histogram normalization processing, gradation processing, etc.
・ Change of processing contents by system information,
It is like this. Hereinafter, the processing procedure of the present embodiment will be described in this order.
[0094]
(1) Irradiation field recognition processing:
By the way, when taking a radiographic image, for example, in order to prevent radiation from being applied to a portion not required for diagnosis, or to a portion not required for diagnosis, radiation scattered in this portion is used for diagnosis. In order to prevent the resolution from being reduced by being incident on a required portion, a radiation non-transparent material such as a lead plate is installed in a part of the subject 5 or the radiation generator 30 so that the radiation field to the subject 5 is irradiated. Irradiation field restriction is performed to limit the above.
[0095]
When this irradiation field stop is performed, if level conversion processing and subsequent gradation processing are performed using the image data of the irradiation field area and the irradiation field area, the image data in the irradiation field is determined by the image data of the irradiation field area. Image processing of a part required for diagnosis is not performed properly. For this reason, the image processing unit 26 performs irradiation field recognition processing for determining the irradiation field inner region and the irradiation field outer region.
[0096]
In the irradiation field recognition processing, for example, a method disclosed in Japanese Patent Application Laid-Open No. 63-259538 is used, and a line from a predetermined position P on the imaging surface toward the end side of the imaging surface as shown in FIG. For example, differentiation processing is performed using the above image data. As shown in FIG. 6B, the differential signal Sd obtained by this differentiation processing has a signal level that increases at the irradiation field edge portion. Therefore, the signal level of the differential signal Sd is determined to determine one irradiation field edge candidate point. EP1 is required. A plurality of irradiation field edge candidate points EP1 to EPk are obtained by performing the process of obtaining the irradiation field edge candidate points radially about a predetermined position on the imaging surface. An irradiation field edge portion is obtained by connecting adjacent edge candidate points of the plurality of irradiation field edge candidate points EP1 to EPk obtained in this way with straight lines or curves.
[0097]
Moreover, the method shown by Unexamined-Japanese-Patent No. 5-7579 can also be used. In this method, when the imaging surface is divided into a plurality of small areas, the radiation dose of the radiation is reduced substantially uniformly in the small areas outside the irradiation field where radiation irradiation is blocked by the irradiation field stop. Becomes smaller. In addition, in a small region within the irradiation field, the radiation value is modulated by the subject, so that the dispersion value is higher than that outside the irradiation field. Further, in a small region including the irradiation field edge portion, the portion with the smallest radiation dose and the portion with the radiation dose modulated by the subject coexist, so the dispersion value is the highest. From this, the small area including the irradiation field edge portion is determined by the dispersion value.
[0098]
Moreover, the method shown by Unexamined-Japanese-Patent No. 7-181609 can also be used. In this method, image data is rotated about a predetermined center of rotation, and rotation is performed until the boundary line of the irradiation field becomes parallel to the coordinate axis of the orthogonal coordinates set on the image by the parallel state detection means. When the state is detected, the linear equation of the boundary before rotation is calculated by the linear equation calculation means based on the rotation angle and the distance from the rotation center to the boundary line. Thereafter, by determining a region surrounded by a plurality of boundary lines from a linear equation, the region of the irradiation field can be determined. When the irradiation field edge portion is a curve, for example, one boundary point is extracted based on the image data by the boundary point extracting means, and the next boundary point is extracted from the boundary candidate point group around this boundary point. Similarly, by sequentially extracting boundary points from the boundary candidate point group around the boundary points, it is possible to determine whether the irradiation field edge portion is a curve.
[0099]
(2) Input image quality determination process:
At this stage, whether or not the input radiation image is appropriate is determined by the following procedure.
(1) Check the maximum and minimum pixel values of the input radiation image.
(2) If the maximum pixel value reaches the maximum pixel value specified by the device, the user is warned that the signal value is saturated and the radiation dose is adjusted correctly. Prompt for confirmation.
(3) Check the pixel value between the maximum value and the minimum value, and if the value is larger than the predetermined value, or smaller than another predetermined value, the histogram width is It warns that it is extremely wide or narrow, and prompts you to confirm that the tube voltage and other adjustments are correct.
[0100]
The warning (output of the input image quality determination signal) may be displayed on a display such as the image display device 22 or may be a synthesized voice.
As described above, in this embodiment, the image processing unit 26 constitutes an input image quality determination unit, which determines the quality of the input radiation image and outputs an input image quality determination signal. To do.
[0101]
In the processing of this embodiment, when performing image processing on the image data of the radiographic image formed corresponding to the amount of radiation transmitted through each part of the subject, the quality of the radiographic image is determined, and the quality of the input image is determined. Since the determination signal is output, it is possible to perform processing only on an image more suitable for diagnosis.
[0102]
The input image quality determination unit includes an input image distribution state detection unit for detecting data indicating a distribution state of image data of a radiographic image formed corresponding to the amount of transmitted radiation. It is desirable to determine the quality of the input image based on a comparison between a predetermined value and data indicating the distribution state of the input image data detected by the image distribution detection means.
[0103]
The image processing apparatus further includes an area setting unit that sets an image area for determining image processing conditions by analyzing image data of a radiographic image formed corresponding to the amount of transmitted radiation passing through each part of the subject. It is desirable that the image distribution state detection means detects data indicating a distribution state of data in the image area. Further, as the data indicating the distribution state of the input image data detected by the input image distribution state detecting means, the image data is distributed within a predetermined range and a substantially maximum value, a substantially minimum value, a parameter indicating the degree of dispersion. The quality of the input image is determined based on at least one of the ratio of the image data, the parameter indicating the degree of dispersion of the image data within the predetermined range, and the parameter indicating the degree of separation by the image data discriminant analysis method. It is desirable. Further, it is desirable that the input image quality determination means determines the quality of the input image based on whether or not the input image signal is saturated. It is desirable to have an input image warning signal output means for outputting a signal when the input image is not appropriate.
[0104]
(3) Processing key selection pass / fail judgment processing:
When performing gradation processing, a processing key is selected. This is because more stable processing is performed by changing the processing method depending on the part or the like. In the quality determination of the process key selection, it is determined whether or not the correct process key has been selected for the imaged part. This is done by the following method.
(1) The maximum / minimum pixel value of the input radiation image and the ratio of the signal value between the low signal value side and the high signal value side with the median value as the boundary are examined.
(2) Check the pixel value between the maximum value and the minimum value, and if the value is significantly different from the value set in consideration of the value obtained when imaging the part to be processed with the normally selected key, The ratio between the low signal value side and the high signal value side obtained in (1) is significantly different from the value set in consideration of the ratio of the signal value obtained when the region to be processed with the normally selected key is imaged. If so, warn the user that the selected process key may be incorrect.
[0105]
In addition to the above determination method, a method using the shape of a histogram is also conceivable. In the case of a radiographic image, for example, in the case of a chest front image, the histogram has a shape such as two peaks with a large valley in between. It is also possible to determine whether or not the selected process is correct using such a feature.
[0106]
The warning may be displayed on a display such as the image display unit 22 or may be a synthesized voice.
As described above, in this embodiment, the image processing unit 26 constitutes an image processing unit (processing key) quality determination unit, determines the quality of the selected image processing unit (processing key), and the image The processing means (processing key) outputs a pass / fail judgment signal.
[0107]
In the processing of this embodiment, when performing image processing on image data of a radiographic image formed corresponding to the amount of radiation passing through each part of the subject, the processing key can be selected from a plurality of processing keys. In addition, since the quality of the selected processing key is judged and the processing key quality judgment signal is output, it becomes possible to select an appropriate processing, and more suitable failure for diagnosis. Less processing can be performed.
[0108]
Note that the image processing apparatus includes input image distribution state detection means for detecting data indicating a distribution state of image data of a radiographic image formed corresponding to the radiation transmission amount, and the processing key pass / fail determination means includes the input image. It is desirable to determine whether the selected processing key is good or bad based on a comparison between a predetermined value and data indicating the distribution state of the input image data detected by the distribution detecting means.
[0109]
An area in which the input image distribution state detection means sets an image area for determining image processing conditions by analyzing image data of a radiographic image formed corresponding to the amount of radiation transmitted through each part of the subject It is desirable to have setting means and detect data indicating the distribution state of the data in the image area.
[0110]
Further, as the data indicating the distribution state of the input image data detected by the processing unit distribution state detection unit, the image data is distributed within a predetermined range and a substantially maximum value, a substantially minimum value, a parameter indicating the degree of dispersion. Based on at least one of the ratio of the image data, the parameter indicating the degree of dispersion of the image data within the predetermined range, and the parameter indicating the degree of separation by the determination analysis method of the image data, the selected image processing means It is desirable to judge pass / fail.
[0111]
It is also desirable to have processing means warning signal output means for processing signals when the selected processing means is not appropriate.
(4) ROI recognition processing:
When the irradiation field recognition is performed, the image processing unit 26 converts the distribution of the image data DT from the radiation image reader into a desired level distribution, and then the level distribution of the image data DT from the radiation image reader. A region (hereinafter referred to as “region of interest” or “ROI (Region Of Interest)”) is determined. By determining a representative value from the image data in the ROI set here and converting the representative value to a desired level, image data having a desired level distribution can be obtained.
[0112]
For example, the setting of the ROI to the rib cage in the chest front process is set according to the following procedure. First, the left and right lines are determined by the following S1 to S3.
S1: Find vertical projections (cumulative values in one direction of the data) of the upper and lower parts of the image data and the part that excludes the outside of the irradiation field (FIG. 7A and FIG. 7). b)).
S2: A point where the signal value has a minimum value (referred to as Pc) in the range of 1/3 of the central portion (1/3 * x to 2/3 * x in FIG. 7) from the obtained vertical projection. The middle line column (Xc).
S3: The calculated vertical projection value is calculated from the 1/3 column (2/3 * x, 1/3 * x in FIG. 7) of the left and right images to the outside (left and right direction) of the image. A point below the threshold (Tl, Tr) is searched for, and the first point is taken as the left and right ends (Xl, Xr) of the lung field. As the threshold value, the maximum value (Plx, Prx) of the projection value is updated from the column of Pc and 1/3 of the entire image toward the outside (left-right direction) of the image,
Tl = ((k1-1) * Plx + Pc) / k1
Tr = ((k2-1) * Prx + Pc) / k2
And Here, k1 and k2 are constants.
[0113]
Next, the upper and lower lines are determined by S4 and S5.
S4: Take a horizontal projection in the section determined in the above step (FIG. 7C).
S5: The horizontal direction obtained from the 1/4 and 1/2 lines (1/4 * y, 1/2 * y in FIG. 7) of the entire image in the upper and lower directions toward the outside (vertical direction) of the image A point whose projection value is equal to or less than the threshold value is searched for, and the first point is set as the upper and lower ends (Yt, Yb) of the right lung field. As the threshold, each of the whole image
The maximum value (Ptx, Pbx) of the projection value in the range of 1/4 * y to 1/2 * y and 1/2 * y to 4/5 * y and the line of the maximum value outside the image (vertical direction) Using the minimum projection value (Ptn, Pbn) in the range of
Tt = ((k3-1) * Ptx + Ptn) / k3
Tb = ((k4-1) * Pbx + Pbn) / k4
And Here, k3 and k4 are constants.
[0114]
Further, the parameters k1 to k4 used for obtaining the threshold value by the above formula are obtained empirically.
The setting of the ROI is not limited to the case where the profile is analyzed and set as described above. For example, as shown in JP-A-5-7578, the image data of each pixel and the discriminant analysis method are used. Threshold values determined by the above are compared, and an identification code is added to each pixel based on the comparison result. Labeling is performed for each pixel group having consecutive identification codes indicating that the threshold value is greater than or equal to the threshold value. The field area is extracted, and the ROI can be set so as to include the lung field and the subdiaphragm area on the basis of the extracted lung field area.
[0115]
Further, as disclosed in JP-A-62-26047, a lung field region is recognized by detecting a lung field contour using a boundary point tracking method, and the lung field and the subdiaphragm are based on the recognized lung field region. The ROI may be set so as to include the region.
[0116]
Furthermore, since it is generally performed that the most important part for diagnosis is taken as the center of the irradiation field, a region such as a circle or a rectangle is set at the center of the irradiation field region and the ROI is set. You can also
[0117]
(5) ROI pass / fail judgment processing:
It is determined whether or not the ROI recognized and set as described above is a correct area. Here, chest front processing is taken as an example.
[0118]
(5-1) ROI pass / fail judgment based on the maximum signal value in the lung field:
Whether the ROI is good or bad using the maximum signal value in the lung field is determined according to the following procedure. S1: The threshold value is lowered in order from the maximum value in the image, and a binarized image is created in which the threshold value is 1 and the threshold value is 0 (see FIG. 8).
S2: The created binarized image is examined, and an island-like region of pixel value 1 that is not in contact with the irradiation field edge is detected. For the detection of island regions, methods using boundary tracking and labeling can be considered.
S3: The region obtained in S2 above is set as the maximum pixel value region in the lung field. Investigate whether this region in ROI is included, and if it is included, determine that it is set to correctly include the lung field region, and if not, include the region where ROI was detected To enlarge.
S4: When a signal value higher than the maximum signal value of the detected area is included in the ROI, it is determined that an unaccompanied area is included, and the process is switched to a process by another method or a process set as a default. As another method, for example, an example given in the embodiment of Japanese Patent Application No. 10-276095 can be considered.
[0119]
As another means for obtaining the maximum signal value region in the lung field, the lung field region is recognized by extracting the contour of the lung field using the boundary tracking method (see Japanese Patent Laid-Open No. 62-26047), and the maximum in the lung field region is detected. A method of determining the maximum signal value region in the lung field by obtaining the signal value is also conceivable. In addition, the lung field was extracted using the Watershed method (reference: Meyer, and S. Beucher: Morphological Segmentation. J. of Visual Comm. And Image Represent., 1,1: 21-46, 1990). A method is also conceivable in which the maximum signal value of each divided region in the field region is obtained and the region including the largest signal value is set as the lung field maximum signal value region.
[0120]
(5-2) Determination of ROI quality using subdiaphragm region:
Whether the ROI includes the subdiaphragm, which is a region other than the lung field, is determined by the following methods S1 to S5.
S1: A band-like region having a width of 10 pixels (see FIG. 9A), and the difference diff between the maximum signal value and the minimum signal value in the region excluding 1/10 from the larger pixel value in the region, and The separation degree sep is calculated by discriminant analysis. This is because the separation degree diff and difference sep are calculated in a region that does not include the missing part (see FIGS. 9B and 9C). The removal of this blank portion is not limited to the above-described method, and for example, a method using a discriminant analysis method can be considered.
S2: The above S1 region is shifted by 5 pixels, and the separation degree sep and the difference diff are obtained in each region.
S3: The maximum values of all the obtained separations sep and difference diff are set to max_sep and max_diff, respectively.
S4: The separation degree sep and the difference diff of each region are checked again, and a region in which three regions satisfying sep <max_sep / 2 and diff <max_diff * 3/4 are continued is searched. By doing so, it is possible to detect a subdiaphragm region (see FIG. 9C) in which the signal difference is small and the concentration is low.
S5: When the subdiaphragm region is included in the ROI by the above processing of S4, the ROI is reduced so that the region is not included.
[0121]
If it is determined that the processing has failed by the above processing (5-1) or (5-2), an image area warning signal may be output and at the same time prompting the operator to warn. This may be a method of displaying on a display or a warning by synthesized speech.
[0122]
Also, the above (2) input image pass / fail determination process and (3) selection process key pass / fail determination process may be performed after the above (4) ROI recognition process or (5) ROI pass / fail determination process. Conceivable. In this case, pass / fail can be determined based on the data in the ROI. In addition, when it is determined that the ROI is defective or not, it is determined that the input image is defective or the selected processing key is incorrect, and a warning is given to the operator.
[0123]
As described above, in this embodiment, the image processing unit 26 constitutes the image area position pass / fail judgment means, judges the pass / fail of the set image area position (ROI), and outputs the image area position judgment signal. In addition to outputting, if it is determined to be defective, the ROI is automatically corrected and an image area warning signal is output.
[0124]
In the processing of this embodiment, an image region (ROI) for determining image processing conditions by analyzing image data of a radiographic image formed corresponding to the amount of transmitted radiation passing through each part of the subject is set. The image processing conditions are determined based on the statistical properties of the image data in the set image area, and the quality of the set image area position is determined. It becomes possible to determine appropriate image processing conditions. For this reason, a radiographic image more suitable for diagnosis can be obtained.
[0125]
The image area position quality determination means preferably determines the quality of the image area position based on the statistical properties of the image data in the image area set by the area setting means.
[0126]
In addition, it is preferable that the image area position quality determination unit determines the quality of the image area position by using position information in the entire image of the image area set by the area setting unit.
[0127]
In addition, the image area position pass / fail determination means includes, as data indicating statistical properties in the image area set by the area setting means, a substantially maximum value, a substantially minimum value of the image data, and a parameter indicating a degree of dispersion. , Based on at least one of a ratio of the image data distributed within the predetermined range, a parameter indicating the degree of dispersion of the image data within the predetermined range, and a parameter indicating the degree of separation by the discriminant analysis method of the image data, It is desirable to determine the quality of the image area position.
[0128]
Further, the image area position pass / fail judgment means has a specific area setting means for setting a specific area in the image separately from the image area by the image area determination means, and the area setting means as position information in the entire image It is desirable to determine whether the image area position is good or not based on whether or not the image area set by (1) includes the area set by the specific area setting means. The area set by the specific area setting means is preferably a predetermined area in the image. It is desirable that the area set by the specific area setting means is at least one of a maximum signal value area or a minimum signal value area in the subject. Further, when the defect is determined based on the image area position pass / fail determination signal, the area setting unit sets the data indicating the statistical properties in the image area in a direction approaching a desired value. It is desirable to provide area setting resetting means for resetting the area. Further, based on the image area position pass / fail determination signal, the area set by the area setting unit is reset in a direction in which the position of the image area in the entire image approaches a desired position when a defect is determined. It is desirable to provide an area setting resetting means. Further, it is desirable to provide failure determination time processing means changing means for performing processing by another preset processing means when a defect is determined based on the image area position pass / fail determination signal. Further, it is desirable to have an image area warning signal output means for outputting a signal when a defect is determined based on the image area position pass / fail determination signal. The failure determination time processing means changing means is preferably default image area setting means for setting the image area to a preset area.
[0129]
(6) Histogram normalization processing:
First, representative values D1 and D2 are set from a cumulative histogram of image data in the ROI. The representative values D1 and D2 are set as image data levels at which the cumulative histogram has a predetermined ratio m1 and m2.
[0130]
When the representative values D1 and D2 are set, the normal values for converting the representative values D1 and D2 into desired reference values S1 and S2 as shown in FIG. 10 with reference to a normalization lookup table provided in advance. Processing is performed. Here, the characteristic curve CC indicates the level of a signal output in accordance with the radiation dose of the radiation applied to the imaging panel 41. The normalization processing lookup table is generated by calculation using an inverse function of the function indicating the characteristic curve CC of the imaging panel 41. Of course, normalization processing may be performed by arithmetic processing without using the normalization processing lookup table.
[0131]
As shown in FIG. 11, by this normalization processing, even if the radiation doses Ra to Rb are lower than the doses R1 to R2 at which the image data of the desired reference values S1 to S2 can be obtained, the desired reference Since the image data of the values S1 to S2 can be obtained, the exposure amount of the subject can be reduced, and at the same time, the variation in the signal distribution due to the difference in the body shape of the subject can be corrected.
[0132]
Next, gradation processing is performed using normalized image data DTreg obtained by normalization processing. In the gradation processing, for example, a gradation conversion curve as shown in FIG. 12 is used, and the normalized image data DTreg is output with the reference values S1 and S2 of the normalized image data DTreg as parameter values S1 ′ and S2 ′. Converted to image data DTout. The levels S1 ′ and S2 ′ correspond to predetermined luminance or photographic density in the output image.
[0133]
The above tone conversion curve is preferably a continuous function over the entire signal region of the normalized image data DTreg, and its differential function is also preferably continuous. Moreover, it is preferable that the sign of the differential coefficient is constant over the entire signal region.
[0134]
In addition, since the preferable gradation conversion curve shape and levels S1 ′ and S2 ′ differ depending on the imaging region, imaging position, imaging conditions, imaging method, etc., the gradation conversion curve may be created for each image each time. For example, as shown in Japanese Patent Publication No. 5-26138, a plurality of basic gradation conversion curves are stored in advance, and one of the basic gradation conversion curves is read and rotated and translated. Thus, a desired gradation conversion curve can be easily obtained. The image processing unit 26 is provided with a gradation processing lookup table corresponding to a plurality of basic gradation curves, and is obtained by referring to the gradation processing lookup table based on the normalized image data DTreg. By correcting the image data according to the rotation and translation of the basic gradation conversion curve, output image data DTout subjected to gradation conversion can be obtained. In the gradation conversion process, not only the two reference values S1 and S2 but also one reference value or three or more reference values may be used.
[0135]
Here, the selection of the basic gradation curve and the rotation and translation of the basic gradation curve are performed based on the imaging region, imaging position, imaging conditions, imaging method, and the like. When these pieces of information are input as management information using the input device 27, the basic gradation curve can be easily selected and the rotation direction of the basic gradation curve by using this management information. And the amount of translation can be determined. Further, the levels of the reference values S1 and S2 may be changed based on the imaging region, the imaging posture, the imaging conditions, and the imaging method.
[0136]
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 preferred gradation may differ depending on the image output method.
[0137]
(7) Dynamic range compression processing and frequency processing:
Next, frequency processing (frequency enhancement processing) and dynamic range compression processing will be described. In the frequency enhancement process, for example, the function F is determined by a method shown in Japanese Patent Publication Nos. 62-62373 and 62-62376 in order to control the sharpness by the non-sharp mask processing shown in the following equation.
[0138]
Sout = Sorg + F (Sorg−Sus)
Sout is image data after processing, Sorg is image data before frequency enhancement processing, and Sus is unsharp data obtained by processing the image data before frequency enhancement processing by averaging processing or the like.
[0139]
In this frequency enhancement process, for example, F (Sorg−Sus) is set to β × (Sorg−Sus), and β (enhancement coefficient) is changed substantially linearly between the reference values T1 and T2 as shown in FIG. . Further, as shown by the solid lines in FIG. 14, when values “A” and “B” are set to emphasize low luminance, β from the reference value T1 to the value “A” is maximized, and the value “ B "to the reference value T2 is minimized. In addition, from the value “A” to the value “B”, β is almost linear.
To be changed. When emphasizing high luminance, as shown by a broken line, β from the reference value T1 to the value “A” is minimized and maximized from the value “B” to the reference value T2. In addition, from the value “A” to the value “B”, β changes almost linearly. Although not shown, when medium luminance is emphasized, β of values “A” to “B” is maximized. As described above, in the frequency enhancement processing, the sharpness of an arbitrary luminance portion can be controlled by the function F.
[0140]
Further, the frequency enhancement processing method is not limited to the non-sharp mask processing, and a technique such as a multi-resolution method disclosed in Japanese Patent Laid-Open No. 9-44645 may be used. In the frequency enhancement process, the frequency band to be enhanced and the degree of enhancement are set based on the imaging region, the imaging position, the imaging conditions, the imaging method, etc., as in the selection of the basic gradation curve in the gradation processing. .
[0141]
In the dynamic range compression processing, the function G is determined by the method disclosed in Japanese Patent Publication No. 266318 in order to perform control to make the density range easy to see by the compression processing shown in the following equation.
[0142]
Stb = Sorg + G (Sus)
Note that Stb is image data after processing, Sorg is image data before dynamic range compression processing, and Sus is unsharp data obtained by processing image data before dynamic range compression processing by averaging processing or the like.
[0143]
Here, as shown in FIG. 15A, G (Sus) has a characteristic that G (Sus) increases when the unsharp data Sus becomes smaller than the level “La”. The image data Sorg shown in FIG. 15B is image data Stb in which the dynamic range on the low density side is compressed as shown in FIG. 15C. Further, as shown in FIG. 15D, when G (Sus) has such characteristics that G (Sus) decreases when the unsharp data Sus becomes larger than the level “Lb”, The density is low, and the dynamic range on the high density side of the image data Sorg shown in FIG. 15B is compressed as shown in FIG. In the dynamic range compression processing, the correction frequency band and the degree of correction are set based on the imaging region, the imaging posture, the imaging conditions, the imaging method, and the like.
[0144]
Here, the reference values T1 and T2 and the values “A” and “B” or the levels “La” and “Lb”, which are processing conditions in the frequency enhancement processing and dynamic range compression processing, are representative value D1 and D2 determination methods. It is calculated | required by the same method.
[0145]
(8) Change of processing contents by information from the system:
By changing the processing contents according to the diagnostic purpose, patient information and processing information (for example, reprocessing rate, etc.) obtained from, for example, the HIS or RIS () radiation department information system or the device itself as information via the network More stable processing can be performed. Examples are given below.
[0146]
(1) Changes in processing based on diagnostic purpose and patient information
As a processing change for diagnostic purposes, if you want to diagnose both bone and soft parts in the image, gradation processing is performed with a relatively weak contrast to obtain an image with a wide dynamic range. In addition, when only the bone part is an area of interest in diagnosis, it is conceivable to obtain an image more suitable for diagnosis by performing gradation processing with strong contrast. These changes may be made by changing the ROI or by changing the creation method (such as parameters) when creating the lookup table.
[0147]
Moreover, as a process change by patient information, the method of changing a process according to a patient's age, sex, height, and weight can be considered. For example, the size of the rib cage varies with age even in the same chest image. Therefore, it is possible to reduce processing failures by changing the setting range when setting the ROI depending on the patient age. In addition, a method of estimating the degree of obesity based on gender, weight, and height, and changing the gradation so that the soft region can be seen according to the degree of obesity is also conceivable. In this way, gradation processing independent of the body shape can be performed.
[0148]
Furthermore, as an example of changing the process from a plurality of processes according to the diagnostic purpose, when the diagnostic purpose is a follow-up of a medical condition, a process in which the contrast is fixed and the change in the medical condition is easily recognized (for example, Japanese Patent Application No. 10-276095 (see application)).
[0149]
In addition, dynamic range compression processing and frequency processing can be performed more effectively for diagnosis by changing the processing content based on information of HIS and RIS. For example, the frequency range of the diagnostic object of interest differs between when a diagnosis of a tumor or the like is performed and when a diagnosis of tuberculosis or the like is performed. From this, it is conceivable to change the frequency band to be emphasized or its intensity according to the purpose of diagnosis. In addition, by estimating the degree of obesity based on the patient's gender, weight, height, etc., and changing the strength of the dynamic range compression process according to the value, soft tissue such as skin and bone without depending on the patient's body type It may be possible to make the appearance of the image constant.
[0150]
Instead of changing the above-mentioned changes according to the purpose of diagnosis or patient information, a method of changing according to the preference of the attending physician is also conceivable.
(2) Change of processing based on processing information
A method of changing the ROI recognition process pass / fail or the pass / fail judgment threshold value of the image after the gradation process according to the reprocessing rate of the process stored in the system / radiation image processing apparatus or the like can be considered. In this case, the failure image can be recognized without erroneously recognizing the correct image by changing the threshold value so that the process with a higher reprocessing rate is less likely to be determined to be correct.
[0151]
As described above, in this embodiment, the image processing unit 26 obtains the information necessary for image processing from the system and apparatus, and the information obtained using the processing information obtaining means. The image processing means changing means for changing the processing means is included.
[0152]
In the processing of this embodiment, information necessary for image processing is obtained from the system and apparatus when image processing is performed on image data of a radiographic image formed corresponding to the amount of radiation transmitted through each part of the subject. Since the image processing means is changed according to this information, processing is performed in consideration of information obtained from the device / system such as the diagnostic purpose and processing success rate, and processing with fewer failures suitable for diagnosis It becomes possible to do.
[0153]
In addition, it is preferable that a network connection unit for connecting to the network is provided, and the information obtained by the processing information acquisition unit is information obtained through the network.
[0154]
In addition, it is preferable that a plurality of image processing units (see FIG. 16) are provided, and the image processing unit changing unit selects one or a plurality of image processing units from the plurality of image processing units. Further, it is desirable that the image processing means changing means changes processing parameters.
[0155]
<Other embodiments>
In addition, it is not necessary to perform each process in the above (1)-(8) using all the information of a radiographic image, It is desirable to use the image reduced by the thinning process. In this case, since the amount of data is reduced, the processing speed can be improved and the memory capacity can be saved. In this case, it is preferable to use image data that has been thinned so that the effective pixel size of the reduced image by thinning is 0.4 mm to 10.0 mm, preferably 1.0 mm to 6.0 mm.
[0156]
【The invention's effect】
As described above in detail, according to the present invention, the following effects can be obtained.
(1) In the first invention, when setting image areas for determining image processing conditions by analyzing image data of a radiographic image formed corresponding to the amount of radiation transmitted through each part of the subject Determining the image processing conditions based on the statistical properties of the image data in the set image area, and determining whether the set image area position is good or bad, Since warning is performed, an appropriate image processing condition can be determined at an appropriate image region position. For this reason, a radiographic image more suitable for diagnosis can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an image processing procedure of a radiation image processing apparatus of the present invention.
FIG. 2 is a configuration diagram showing a configuration of a radiographic image processing apparatus according to the present embodiment.
FIG. 3 is a configuration diagram showing a configuration of a radiation image reader according to the present embodiment.
FIG. 4 is a configuration diagram showing a configuration using another radiation image reader according to the present embodiment.
FIG. 5 is a configuration diagram showing a configuration of a controller according to the present embodiment.
FIG. 6 is an explanatory diagram for explaining irradiation field recognition processing according to the present embodiment.
FIG. 7 is an explanatory diagram for explaining recognition of ROI in the present embodiment example;
FIG. 8 is an explanatory diagram for explaining ROI determination in the present embodiment;
FIG. 9 is an explanatory diagram for explaining ROI determination in the present embodiment;
FIG. 10 is an explanatory diagram for explaining level conversion in the embodiment.
FIG. 11 is an explanatory diagram showing normalization processing in the embodiment.
FIG. 12 is an explanatory diagram showing gradation conversion characteristics in the present embodiment example.
FIG. 13 is an explanatory diagram showing a relationship between an enhancement coefficient and image data in the present embodiment.
FIG. 14 is an explanatory diagram showing a relationship between an enhancement coefficient and image data in the present embodiment.
FIG. 15 is an explanatory diagram for describing dynamic range compression processing in the present embodiment;
FIG. 16 is an explanatory diagram for explaining a state of a plurality of processes in the embodiment.
FIG. 17 is an explanatory diagram for explaining a reading unit used in the present embodiment;
FIG. 18 is an explanatory diagram for explaining a reading unit used in the present embodiment;
[Explanation of symbols]
10 Controller
26 Image processing unit
30 Radiation generator
40,60 Radiation image reader
41 Imaging panel
44 Scanning drive unit
46 Image data generation circuit
48 Reading control circuit
61 Conversion panel
62 Light beam generator
63 Scanning section
64 Reflector
65 Condenser
66 Filter
67 Photomultiplier
70 Current / voltage converter
75 Reading control unit

Claims (4)

An area setting means for setting an image area for determining image processing conditions by analyzing image data of a radiographic image formed corresponding to the amount of radiation transmitted through each part of the subject, and setting by the area setting means Image processing condition setting means for determining image processing conditions based on the statistical properties of the image data in the image area, and determination of the quality of the image area position set by the area setting means, Image region position pass / fail judgment means for outputting a signal;
Is configured to include a,
The image area position pass / fail determination means determines the pass / fail of the image area position by using position information in the entire image of the image area set by the area setting means. In addition, there is a specific area setting means for setting a specific area in the image, and whether the image area set by the area setting means includes the area set by the specific area setting means as position information in the entire image Judge whether the image area position is good or bad by
A radiographic image processing apparatus characterized by that. The area set by the specific area setting means is a predetermined area in the image.
The radiation image processing apparatus according to claim 1. The area set by the specific area setting means is at least one of a maximum signal value area or a minimum signal value area in the subject;
The radiation image processing apparatus according to claim 1. A failure determination time processing means changing means for performing processing by another preset processing means when a defect is determined based on the image region position pass / fail determination signal;
The failure determination time processing means changing means is a default image area setting means for setting an image area to a preset area.
The radiographic image processing apparatus according to claim 1 , wherein the radiographic image processing apparatus is a radiographic image processing apparatus.

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