JP3861405B2 - Radiation image processing method and radiation image processing apparatus - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a radiation image processing method using a radiation image conversion panel such as a stimulable phosphor (stimulable phosphor plate) and an improvement in storage operation in a radiation image processing apparatus.
[0002]
[Prior art]
When a certain type of phosphor is irradiated with radiation (X-rays, α-rays, β-rays, r-rays, ultraviolet rays, etc.), a part of the radiation energy is accumulated in the phosphors. It is known that when the phosphor is irradiated with excitation light such as visible light, the phosphor exhibits stimulated emission according to the accumulated energy. A phosphor exhibiting such properties is called a storage phosphor or a stimulable phosphor.
[0003]
Using this stimulable phosphor, radiation image information of a human body or the like is once recorded on a storage phosphor (radiation image conversion panel such as a stimulable phosphor plate) provided on the sheet, and this radiation image is recorded. It is possible to scan the conversion panel with excitation light such as laser light to generate stimulated emission light, and photoelectrically read out the obtained stimulated emission light to obtain an image signal.
[0004]
In addition to the radiation image conversion panel, a film sensitive to radiation, a semiconductor detector, or the like can be used.
In such a case, a plurality of images are captured by using a region of one radiation image conversion panel divided into a plurality of regions by photographing called divisional photographing.
[0005]
[Problems to be solved by the invention]
In general, a plurality of images that have been divided and photographed as described above are read as one image by one entire radiation image conversion panel, and processed and output as one image.
[0006]
In this way, when processed as a single image as a whole, each of the plurality of divided images is photographed under different photographing conditions (exposure, photographing method, etc.). There arises a problem that optimum image processing cannot be performed for each image.
[0007]
It is also known to apply different image processing to each of a plurality of images with respect to a plurality of images divided and photographed on one radiation image conversion panel. However, no consideration has been given to storage and management of image data when such different image processing is performed.
[0008]
That is, when processing is performed in units of individual images that are divided and photographed on one radiation image conversion panel in this way, naturally, each of a plurality of images that are divided and photographed is separately provided as separate image data. Will be saved.
[0009]
Therefore, a plurality of images and a plurality of processing conditions are generated for one divided and captured radiation image conversion panel, which makes management of images and processing conditions very troublesome.
[0010]
Further, if the images are stored in the state of the original radiation image conversion panel obtained by separately collecting images that have been subjected to image processing, the management of the images becomes easy. However, there is a drawback that the originality of the image is lost.
[0011]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a radiation image processing method and a radiation image processing apparatus that can easily manage divided images without losing the originality of the image. It is to provide.
[0012]
[Means for Solving the Problems]
Therefore, the invention as means for solving the problems will be described below.
(1) The invention according to claim 1 is a radiographic image processing method for reading an image recorded in a radiographic image conversion means that is divided and imaged by irradiating a plurality of sections and storing it as image data, Level-shift processing is performed to separate the individual images that have been divided and the signal levels are substantially aligned, and the combined images are generated by combining the level-shifted images into one image at the time of divided shooting. A radiation image processing method for obtaining gradation conversion processing characteristics when performing gradation conversion processing on the composite image, and storing the image data of the composite image and the gradation conversion processing characteristics in association with each other It is.
[0013]
The invention according to claim 8 is a radiographic image processing apparatus that reads an image recorded in a radiographic image conversion unit that is divided and imaged by irradiating a plurality of sections and stores the image as image data, and is divided and imaged Level shift processing is performed such that the individual images are separated and the signal levels are substantially aligned, and the individual images subjected to level shift processing are combined into one image at the time of divided shooting to generate a composite image, Image processing means for obtaining gradation conversion processing characteristics when performing gradation conversion processing on the composite image; and control means for associating and storing the image data of the composite image and the gradation conversion processing characteristics in the storage means. A radiation image processing apparatus including the radiation image processing apparatus.
[0014]
In these inventions, level-shift processing is performed on individual images that have been divided and shot, and then a combined image is generated as a single image at the time of divided shooting, and a combined image and gradation conversion processing of the image are performed. By storing in association with the characteristics, it is possible to easily manage images that have been separately shot without losing the originality of the images.
[0015]
(2) According to a second aspect of the invention, gradation conversion processing in Claim 1, characterized in that the gradation conversion processing by the gradation conversion table.
The invention of claim 9, wherein the gradation conversion processing in the image processing unit in the claims 8, characterized in that the gradation conversion processing by the gradation conversion table.
[0016]
In these inventions, by using the gradation conversion table as the gradation conversion processing, it becomes possible to perform the gradation conversion processing easily.
(3) According to a third aspect of the invention, the gradation conversion processing in claims 1 and 2, using the gradation conversion table underlying, depending on the dynamic range of the composite image data, the basic and The gradation conversion process is performed by determining the inclination of the gradation conversion table.
[0017]
Invention of claim 10, wherein the gradation conversion processing in the image processing unit according to claim 8 and claim 9, which uses the gradation conversion table underlying the dynamic range of the composite image data Accordingly, the gradation conversion processing is performed by determining the inclination of the basic gradation conversion table.
[0018]
In these inventions, the gradation conversion process can be easily performed by using the gradation conversion table in which the inclination is determined according to the dynamic range of the composite image.
(4) invention of claim 4, wherein the gradation conversion processing in claims 1 and 2, using the gradation conversion table underlying, depending on the dynamic range of the whole composite image data, the basic The gradation conversion processing is performed by determining the gradient of the gradation conversion table.
[0019]
Invention of claim 11, wherein the gradation conversion processing in the image processing unit according to claim 8 and claim 9, which uses the gradation conversion table underlying, the composite image data overall dynamic The gradation conversion processing is performed by determining the inclination of the basic gradation conversion table according to the range.
[0020]
In these inventions, the tone conversion process can be easily performed by using the tone conversion table in which the inclination is determined according to the dynamic range of the entire composite image data.
[0021]
(5) invention of claim 5, wherein the gradation conversion processing in claims 1 and 2, using the gradation conversion table made up of the core in accordance with the dynamic range of the main image of the divided-captured, The gradation conversion processing is performed by determining the inclination of the basic gradation conversion table.
[0022]
Invention of claim 12, wherein the gradation conversion processing in the image processing unit according to claim 8 and claim 9, which uses the gradation conversion table underlying, the main image according to the segmented imaging The gradation conversion processing is performed by determining the inclination of the basic gradation conversion table according to the dynamic range.
[0023]
In these inventions, the gradation conversion process can be easily performed by using the gradation conversion table in which the inclination is determined according to the dynamic range of the main image related to the divided photographing.
[0024]
(6) The invention described in claim 6 is a gradation conversion table in which the gradation conversion processing characteristics stored in association with the composite image in claims 1 to 5 are basic, and the gradation conversion table. It is characterized by the inclination determined for.
[0025]
According to a thirteenth aspect of the present invention, there is provided a gradation conversion table in which the gradation conversion processing characteristics stored in association with the composite image by the control means according to the eighth to twelfth aspects are basic, and the gradation conversion table. It is characterized by the inclination determined for.
[0026]
In these inventions, the basic gradation conversion table and the inclination determined with respect to the gradation conversion table are stored together with the image as the gradation conversion processing characteristics without losing the originality of the image. It becomes possible to easily manage divided images.
[0027]
(7) According to a seventh aspect of the present invention, the gradation conversion processing characteristic stored in association with the composite image in the first to fifth aspects is a dynamic range of the composite image data as the gradation conversion table. and wherein the at-out inclination determined in accordance.
[0028]
According to a fourteenth aspect of the present invention, the gradation conversion processing characteristic stored in association with the composite image by the control means according to the eighth to twelfth aspects is a dynamic range of the composite image data as the gradation conversion table. and wherein the at-out inclination determined in accordance.
[0029]
In these inventions, the gradation conversion table having the inclination determined according to the dynamic range of the composite image is stored together with the image as the gradation conversion processing characteristics, so that the divided images are taken without losing the originality of the image. Images can be easily managed.
[0030]
(8) In each of the above inventions, the radiation image conversion means corresponds to various image conversion means such as a radiation image conversion panel or a film having sensitivity to radiation.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 is a block diagram showing an example of a radiographic image processing apparatus in each embodiment of the present invention or an apparatus for executing the radiographic image processing method in each embodiment of the present invention.
[0032]
In FIG. 1, a control unit 10 is a control means for controlling the operation of each part of the apparatus, and performs various controls relating to image storage, image processing, etc. in accordance with an instruction input from the operation unit 20 or a built-in operation control program. It is.
[0033]
The scanner 30 is an input device that reads an image. Here, the scanner 30 reads an image of a radiation image conversion panel that has been shot under an instruction for divided shooting, and generates image data.
[0034]
In this embodiment, an example in which a radiation image conversion panel is used as the radiation image conversion means will be described. However, when a film is used as the radiation image conversion means, reading may be performed with a digitizer. In addition to the photostimulable phosphor plate, the radiation image conversion panel also includes a semiconductor detector.
[0035]
The image processing unit 40 is an image processing unit that performs under the instruction of the control unit 10 such as a combination process of a plurality of images shot under an instruction for divided shooting and execution of image processing suitable for each image.
[0036]
The image storage unit 50 is an image storage unit composed of an optical disk device, a magnetic disk device, or the like, and stores and stores image data according to instructions from the control unit 10.
[0037]
The printer 60 is an image output unit that forms an image (hard copy creation) of an image read by the scanner 30 and processed by the image processing unit 40.
The display unit 70 is a display unit that displays an image of various states of the apparatus, radiation images obtained by reading, states in which individual images are combined, and the like.
[0038]
Although FIG. 1 shows a configuration relating to reading and storage, it is assumed that there is also an apparatus that performs imaging on the radiation image conversion panel. For example, the radiographic image conversion panel circulates in the apparatus, and the radiographing, reading, and storing are applicable. In addition, a cassette-type radiation image conversion panel that has been imaged by another imaging apparatus is read and stored by the apparatus of this embodiment.
[0039]
Here, the operation of the present embodiment will be described with reference to FIG. Here, the operation relating to the storage of an image photographed on one radiation image conversion panel under the instruction of divided photographing will be mainly described.
[0040]
The flowchart of FIG. 2 is a routine related to the storage of an image shot under an instruction for divided shooting, and is called by the control unit 10 from the main operation program when necessary.
[0041]
First, imaging is performed on the radiation image conversion panel (S2 in FIG. 2) under the instruction for divisional imaging (S1 in FIG. 2) from the operator. That is, division imaging is performed by irradiating radiation to each of a plurality of sections of the radiation image conversion panel.
[0042]
Then, the scanner 30 collectively reads the images divided and photographed on one radiation image conversion panel (S3 in FIG. 2).
Here, FIG. 3A shows an example of a state in which a single radiographic image conversion panel is imaged under the instruction for divided imaging. For example, the image shown here is taken by dividing one radiation image conversion panel into four sections.
[0043]
The image read by the scanner 30 is supplied to the image processing unit 40 as image data. The image processing unit 40 separates each of the plurality of images obtained by the divided shooting and generates individual image data (S4 in FIG. 2).
[0044]
In this case, the image is cut out and separated so as to include at least a range recognized as one image. Alternatively, although the X-ray irradiation field is determined by the X-ray diaphragm, the X-ray irradiation field is cut out and separated so as to include one range irradiated with the X-ray.
[0045]
When the images read together are as shown in FIG. 3A, the image data separated at this stage is as shown in FIG.
In order to cut out in this way, a known image processing technique is used to separate at least one image into a plurality of images. For example,
(1) Cut out along the contour of the subject of individual images taken separately.
(2) Cut out the subject outline and surrounding area of each image taken separately.
(3) The entire image shown in FIG. 3 (a) is equally divided and cut out in a range including individual images taken separately.
(4) For the range including the individual images taken separately, the margins are cut out so that the margins overlap.
And so on. Further, in this example, each image is divided into four and cut out. However, other than this, the image may be cut out so as to be divided into two so as to include two images.
[0046]
Then, the image processing unit 40 analyzes the density distribution (relationship between the signal value and the appearance frequency) of each separated image, and obtains the shift amount for the level shift processing of each image (S5 in FIG. 2). ).
[0047]
Here, the level shift processing is to translate the signal values of the density distribution of the image data, thereby changing the signal levels of the four images while maintaining the linearity without changing the dynamic range or contrast characteristics. This is a process for aligning variations in shooting conditions by roughly aligning.
[0048]
That is, it is assumed that the density distributions of the four images that have been divided and photographed before the level shift processing are as shown in (1) to (4) in FIG. In this case,
・ Align the center of the concentration distribution (between the minimum and maximum values) ・ Align the centroid of the concentration distribution (centroid obtained by weighting the signal value and appearance frequency) ・ Align the maximum value of the concentration distribution In this way, the image processing unit 40 obtains a shift amount for level shift processing for each image so as to align the signal levels of the four images.
[0049]
Then, based on the shift amount obtained in this way, the image processing unit 40 executes level shift processing for each image (S6 in FIG. 2). As a result, the density distribution of the four images that have been divided and photographed is gathered in a certain region as shown in FIG. This is the same state as when each image was photographed by being irradiated with substantially the same amount of X-rays, and the difference in exposure has been removed.
[0050]
The individual images level-shifted in this way are combined into a single image similar to the state at the time of divided shooting (FIG. 3 (a)), and the combined image (FIG. 3 (c)). )) Is generated (S7 in FIG. 2). In this composite image, the arrangement of the individual images is the same as in the case of divided shooting, but the density distribution of the individual images is substantially aligned by level shift processing, and the difference in exposure is removed while maintaining linearity. It is in a state.
[0051]
Here, the image processing unit 40 analyzes the composite image and obtains gradation conversion processing characteristics (S8 in FIG. 2). This gradation conversion processing characteristic is a characteristic for gradation conversion to match the dynamic range of the image with the dynamic range that can be reproduced by the output device when the image is output (image display or print output). Say.
[0052]
That is, since the dynamic range is relatively narrow in the image of a thin person, it is necessary to perform processing to widen this when outputting. In addition, since the dynamic range of a fat person's image is relatively wide, a process for narrowing it is necessary when outputting.
[0053]
This is shown in FIG. FIG. 5A1 is a density histogram of an image obtained by X-ray imaging of a relatively thin person. When this density histogram image is output, gradation conversion is performed using gradation conversion processing characteristics (T1 in FIG. 5) having a relatively large inclination. In addition, when outputting an image of a density histogram of an image obtained by X-ray imaging of a relatively thick person in FIG. 5A2, gradation conversion is performed using a gradation conversion processing characteristic (T2 in FIG. 5) having a relatively small inclination. By performing such gradation conversion, the dynamic range of the output device (display unit 70, printer 60) can be used effectively.
[0054]
Therefore, the image processing unit 40 obtains the tone conversion processing characteristics in the lookup table (LUT) format from the dynamic range of the density histogram included in the composite image and the dynamic range of the output device.
[0055]
When obtaining the gradation conversion processing characteristics, the gradient (LUT characteristic) of the gradation conversion processing characteristics may be directly obtained according to the composite image, or the reference gradation conversion processing characteristics may be determined. If it exists, the degree (coefficient) of changing the inclination may be obtained. Here, both are referred to as gradation conversion processing characteristics.
[0056]
Further, when obtaining the gradation conversion processing characteristics, the entire density histogram of the composite image may be referred to, or the main image (such as an image taken from the front) of the composite image may be referred to. Alternatively, the composite image may be displayed on the display unit 70, and the operator may designate the main image used to determine the gradation conversion processing characteristics of each image.
[0057]
Then, the control unit 10 stores the synthesized image and the gradation conversion processing characteristic (the gradation conversion processing characteristic itself or a coefficient for changing the basic gradation conversion processing characteristic) in the image storage unit 50 in a state where they are associated with each other. (S9 in FIG. 2). Note that the association processing may be performed by attaching data relating to the association processing to the management data of the image data, and indicating the gradation conversion processing characteristics corresponding to the data to be referred to. You may provide separately the data which show that image data and a gradation conversion process characteristic are mutually related.
[0058]
Therefore, when an image is output to the printer 60 or the display unit 70, the composite image may be output after gradation conversion according to the corresponding gradation conversion processing characteristics. Also, when the operator wants to perform processing with other processing characteristics, the composite image maintains the linearity at the beginning of photographing only by performing the level shift processing, so that a good result can be obtained.
[0059]
The above is the outline of the operation of the apparatus and the procedure of the method according to the present embodiment, and the features and effects are as follows.
(1) After performing level shift processing of individual images taken separately, a combined image is generated as a single image in the state of divided shooting, and the combined image and gradation conversion processing characteristics of the image are obtained. By associating and storing the images, it becomes possible to easily manage the divided images without losing the originality of the images.
[0060]
{Circle around (2)} In the above {circle around (1)}, the gradation conversion process can be easily performed by using the gradation conversion table as the gradation conversion processing characteristic.
(3) In the above (1) or (2), the gradation conversion process can be easily performed by using the gradation conversion table in which the inclination is determined according to the dynamic range of the composite image.
[0061]
(4) In the above (1) or (2), the gradation conversion process can be easily performed by using the gradation conversion table in which the inclination is determined according to the dynamic range of the entire composite image.
[0062]
(5) In the above (1) or (2), it is possible to easily perform the gradation conversion process by using the gradation conversion table in which the inclination is determined according to the dynamic range of the main image related to the divided shooting. Become.
[0063]
(6) In the above (1) to (5), by storing the basic gradation conversion table and the inclination determined with respect to the gradation conversion table together with the image as gradation conversion processing characteristics, It becomes possible to easily manage images taken in a divided manner without losing the originality of the images.
[0064]
(7) In the above items (1) to (5), the gradation conversion table having the slope determined according to the dynamic range of the composite image is stored together with the image as the gradation conversion processing characteristic, thereby improving the originality of the image. This makes it easy to manage the divided images without losing them.
[0065]
【The invention's effect】
As described above in detail, according to each invention described in this specification, the following effects can be obtained.
[0066]
(1) In the radiographic image processing method according to (1) and the radiographic image processing apparatus according to (8), one image in a state at the time of divided imaging is performed after performing level shift processing of each of the divided images. By creating a combined image and storing the combined image and the gradation conversion processing characteristics of the image in association with each other, it is possible to easily manage images that have been divided and shot without losing the originality of the image. Become.
[0067]
(2) In the radiographic image processing method according to (2) and the radiographic image processing apparatus according to (9), in the above (1), the tone conversion processing is performed by using the tone conversion table as the tone conversion processing characteristics. It becomes possible to carry out easily.
[0068]
(3) In the radiographic image processing method according to (3) and the radiographic image processing apparatus according to (10), the gradation conversion table in which the inclination is determined according to the dynamic range of the composite image in the above (1) or (2). By using, it is possible to easily perform the gradation conversion process.
[0069]
(4) In the radiographic image processing method according to (4) and the radiographic image processing apparatus according to (11), in the above (1) or (2), gradation conversion in which the inclination is determined according to the dynamic range of the entire composite image By using the table, the gradation conversion process can be easily performed.
[0070]
(5) In the radiographic image processing method according to (5) and the radiographic image processing apparatus according to (12), in the above (1) or (2), the inclination is determined according to the dynamic range of the main image related to divided imaging. By using the gradation conversion table, the gradation conversion process can be easily performed.
[0071]
(6) In the radiographic image processing method according to (6) and the radiographic image processing apparatus according to (13), in the above-mentioned (1) to (5), a basic gradation conversion table and the gradation conversion table By storing the inclination determined in this way together with the image as the gradation conversion processing characteristics, it becomes possible to easily manage the divided images without losing the originality of the image.
[0072]
(7) In the radiographic image processing method according to (7) and the radiographic image processing apparatus according to (14), in the above (1) to (5), a gradation having a gradient determined according to the dynamic range of the composite image By storing the conversion table together with the image as the gradation conversion processing characteristics, it becomes possible to easily manage the divided images without losing the originality of the image.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an overall configuration of a radiation image processing apparatus used in an embodiment of the present invention.
FIG. 2 is a flowchart showing a state of processing relating to reading and saving of a radiation image according to an embodiment of the present invention.
FIGS. 3A and 3B are explanatory diagrams showing a state of split photographing of a radiographic image and a state of synthesis according to an embodiment of the present invention.
FIG. 4 is an explanatory diagram showing a state of a level shift process of a radiographic image according to an embodiment of the present invention.
FIG. 5 is an explanatory diagram showing a state of gradation conversion processing characteristics of a radiographic image according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Control part 20 Operation part 30 Scanner 40 Image processing part 50 Image storage part 60 Printer 70 Display part

Claims (14)

A radiographic image processing method of reading an image recorded in a radiographic image conversion unit that is divided and imaged by irradiating a plurality of sections and storing it as image data,
Perform level shift processing to separate the individual images taken separately and align the signal level substantially,
For each image that has undergone level shift processing, a combined image is generated by combining the images into one image at the time of divided shooting,
Obtaining a gradation conversion processing characteristic when performing gradation conversion processing on the composite image;
A radiation image processing method, wherein image data of the composite image and the gradation conversion processing characteristics are stored in association with each other. The gradation conversion processing, the radiation image processing method according to claim 1, wherein the by the gradation conversion table is the tone conversion processing. As the gradation conversion process , a basic gradation conversion table is used, and the gradation conversion process is performed by determining the inclination of the basic gradation conversion table according to the dynamic range of the composite image data.
The radiographic image processing method according to claim 1, wherein the radiation image processing method is performed. As the gradation conversion process , a basic gradation conversion table is used, and the gradation conversion process is performed by determining the inclination of the basic gradation conversion table according to the dynamic range of the entire composite image data.
The radiographic image processing method according to claim 1, wherein the radiation image processing method is performed. As the gradation conversion process , a basic gradation conversion table is used, and the gradient conversion process is performed by determining the inclination of the basic gradation conversion table according to the dynamic range of the main image related to divided shooting.
The radiographic image processing method according to claim 1, wherein the radiation image processing method is performed. The gradation conversion processing characteristics stored in association with the composite image are:
The radiation image processing method according to claim 1, wherein the gradation conversion table is a basic and the inclination determined with respect to the gradation conversion table. The gradation conversion processing characteristics stored in association with the composite image are:
Radiographic image processing method according to any one of claims 1 to 5, wherein the at-out inclination determined in accordance with the dynamic range of the composite image data as the gradation conversion table. A radiographic image processing apparatus that reads an image recorded in a radiographic image conversion unit that is divided and photographed by irradiating a plurality of sections and stores the image as image data,
Level-shift processing is performed to separate the individual images that have been divided and the signal levels are substantially aligned, and the combined images are generated by combining the level-shifted images into one image at the time of divided shooting. Image processing means for obtaining gradation conversion processing characteristics when performing gradation conversion processing on the composite image;
Control means for associating and storing image data of the composite image and the gradation conversion processing characteristics in a storage means;
A radiation image processing apparatus comprising: The gradation conversion processing in the image processing unit, the radiation image processing apparatus according to claim 8, characterized in that the tone conversion processing by the gradation conversion table. The gradation conversion processing in the image processing means is one using a gradation conversion table underlying, in response to said dynamic range of the composite image data, to determine the slope of the gradation conversion table underlying The radiographic image processing apparatus according to claim 8, wherein gradation conversion processing is performed. The gradation conversion processing in the image processing means is one using a gradation conversion table underlying, determined in response to said dynamic range of the whole composite image data, the slope of the gradation conversion table underlying The radiation image processing apparatus according to claim 8, wherein gradation conversion processing is performed. The gradation conversion processing in the image processing means is one using a gradation conversion table underlying, the in accordance with the dynamic range of the main image of the divided-captured, the slope of the gradation conversion table underlying The radiographic image processing apparatus according to claim 8, wherein gradation conversion processing is performed by determining the above.   The gradation conversion processing characteristic stored in association with the composite image by the control means is a basic gradation conversion table and an inclination determined with respect to the gradation conversion table. Item 13. The radiographic image processing apparatus according to any one of Items 8 to 12. Claims wherein the gradation conversion processing characteristics that are stored in association with the composite image by said control means, characterized in that the at-out inclination determined in accordance with the dynamic range of the composite image data as the gradation conversion table Item 13. The radiographic image processing apparatus according to any one of Items 8 to 12.

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