JP2903224B2 - Radiation image processing method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a radiation image processing method and apparatus for performing data processing on image data obtained from a recording sheet on which a radiation image is recorded.

(Prior art) Reading a recorded radiation image to obtain image data,
After performing appropriate image processing on the image data, reproduction and recording of the image are performed in various fields. For example, an X-ray image is recorded using an X-ray film having a low gamma value designed to be compatible with later image processing, and this X-ray image is recorded.
The X-ray image is read from the film on which the line image is recorded, converted into an electric signal, the electric signal (image data) is subjected to image processing, and then reproduced as a visible image in a copy photograph or the like, so that the contrast and sharpness are improved. A system capable of obtaining a reproduced image having good image quality such as graininess has been developed (see Japanese Patent Application Laid-Open No. 61-5193).

In addition, the applicant (X-ray, α-ray, β-ray,
Irradiation with gamma rays, electron beams, ultraviolet rays, etc. accumulates a part of this radiation energy, and then irradiation with excitation light, such as visible light, causes a stimulable phosphor (luminous) to emit stimulated emission according to the accumulated energy. Using a photostimulable phosphor), a radiation image of a subject such as a human body is once photographed and recorded on a sheet-shaped stimulable phosphor, and the stimulable phosphor sheet is scanned with excitation light such as a laser beam to radiate. Generates luminescent light, obtains image data by photoelectrically reading the obtained stimulating luminescent light, and outputs a radiation image of the subject as a visible image to a recording material such as a photographic photosensitive material or a CRT based on this image data. A radiation image recording / reproducing system for causing the radiation image to be reproduced has already been proposed (Japanese Patent Laid-Open No. 55-1242).
No. 9, 56-11395, 55-163472, 56-104645
No. 55-116340, etc.).

This system has the practical advantage of being able to record images over a very large radiation exposure area compared to conventional radiographic systems using silver halide photography. That is, in the case of the stimulable phosphor, it has been recognized that the amount of emitted light that is stimulated by excitation after accumulation is proportional to the radiation exposure amount over an extremely wide range. Even if fluctuates considerably, the amount of the stimulating light emitted from the stimulable phosphor sheet is read by the photoelectric conversion means with the reading gain set to an appropriate value and converted into an electric signal. By outputting a radiation image as a visible image on a recording material such as a photographic light-sensitive material or a display device such as a CRT using, a radiation image which is not affected by a change in radiation exposure can be obtained.

In the above-described system, before obtaining image data by reading under optimal reading conditions according to the dose of radiation applied to the stimulable phosphor sheet and the like, scan the stimulable phosphor sheet with a low-level light beam in advance. A pre-read for reading the outline of the radiation image recorded on the sheet is performed, the pre-read image data obtained by the pre-read is analyzed, and then the sheet is irradiated with a light beam having a higher level than the light beam at the time of the pre-read. There is also a system which is configured to perform a main reading by obtaining the image data by reading the radiation image under the optimum reading conditions (Japanese Patent Laid-Open No. 58-67240,
Nos. 58-67241 and 58-67242).

The reading condition is a general term for various conditions that affect the relationship between the amount of stimulated emission light in reading and the output of the reading device. For example, a reading gain, a scale factor, or a scale factor that determines an input / output relationship. , And the power of the excitation light in reading.

Further, the high level / low level of the light beam means that the intensity of the light beam applied per unit area of the sheet is large / small, or the intensity of the stimulating light emitted from the sheet is the light beam. (Having a wavelength sensitivity distribution) means the magnitude of the weighted intensity after weighting the intensity of the light beam irradiated per unit area of the sheet by the wavelength sensitivity. Methods for changing the beam level include using a light beam of a different wavelength, changing the intensity of the light beam emitted from a laser light source, etc., and inserting or removing an ND filter or the like in the optical path of the light beam. Various known methods such as a method of changing the beam intensity, a method of changing the scanning density by changing the beam diameter of the light beam, and a method of changing the scanning speed can be used.

Also, irrespective of whether this pre-reading system is a system that does not perform pre-reading, the obtained image data (including pre-reading image data) is analyzed, and the optimum image processing conditions for performing image processing on the image data are determined. Some systems let you decide. The method for determining the optimum image processing conditions based on the image data is not limited to the system using the stimulable phosphor sheet. For example, image data is obtained from a radiation image recorded on a recording sheet such as a conventional X-ray film. It is also applied to the system.

Various methods have been proposed for analyzing the image data (including the pre-read image data) to determine the optimal reading conditions and image processing conditions. One of the methods is to create a histogram of the image data. (For example, JP-A-60-156055). By obtaining the histogram of the image data, it is possible to know, for example, the maximum value and the minimum value of the image data, the value of the image data at the point where the frequency is maximum, and the like. From these values, the stimulable phosphor sheet, X The features of the radiation image recorded on the recording sheet such as a line film can be grasped. Therefore, by determining the optimal reading conditions and image processing conditions based on this histogram, it is possible to reproduce and output a visible image with excellent observation suitability.

On the other hand, when capturing and recording a radiographic image on a recording sheet, it is necessary to prevent radiation from irradiating a part not necessary for observation of the subject, or to irradiate a part unnecessary for observation with radiation from that part. Since the scattering number is included in the part and the image quality performance deteriorates, shooting is performed using an irradiation field stop that limits the irradiation area of the radiation so that the radiation is irradiated only to the necessary part of the subject and a part of the recording sheet Often.

In this case, for example, on the contour of the radiation field, based on image data corresponding to each pixel along a plurality of radial lines connecting a predetermined point included in the radiation field and the end of the sheet. The contour points are determined for each of the above line segments, and the area surrounded by the lines along these contour points is recognized as the radiation field (see JP-A-63-259538). Then, reading conditions and image processing conditions are obtained based on image data corresponding to the inside of the radiation irradiation field.

(Problems to be Solved by the Invention) A visible image is displayed on a CRT or the like based on image data obtained by performing reading and image processing by using appropriate reading conditions and image processing conditions obtained as described above. Is reproduced, or a visible image is reproduced and output on a film using, for example, a laser printer or the like, so that the visible image is provided for observation.

However, when the original radiation image corresponding to the visible image is obtained by imaging using an irradiation field aperture, the area outside the irradiation field is an area to which almost no radiation was irradiated at the time of imaging, Observe the high brightness of the area outside the irradiation field of the visible image displayed on the CRT, and the low density of the area outside the irradiation field of the visible image reproduced and output to the film. Even if it is excellent in suitability, light from outside the radiation irradiation field is strongly incident on the eyes, so that it is very difficult to see. In order to eliminate this invisibility,
Until now, CR has been used to block light from outside the radiation field.
In some cases, observation was performed with a shielding plate or the like arranged on the front of the T or the front of the film.

However, the shape and size of the radiation field may be various, and it is troublesome to adjust the position of the shielding plate each time.In addition, the above-mentioned shielding plate allows the region inside the radiation field and the region outside the radiation field to be adjusted. It is difficult to clearly cover only the area outside the irradiation field, and it is difficult to cover the surrounding area inside the irradiation field, and the surrounding area may deviate from the observation target, or light may leak from a part outside the irradiation field. For example, there is a problem that the deterioration of observation suitability of a visible image cannot be avoided.

In view of the above problems, the present invention does not require the use of a shielding plate or the like that covers a part of the front surface of a visible image, and obstructs observation by strong light from an area other than the radiation irradiation field being incident on the eyes. It is an object of the present invention to provide a radiation image processing method and apparatus capable of obtaining a visible image without any problem.

(Means for Solving the Problems) The radiation image processing method of the present invention recognizes the radiation field based on radiation field recognition image data representing a radiation image having a radiation field, and generates an image representing the radiation image. In order to make the area outside the radiation field of the visible image reproduced based on the image data for reproduction have low luminance or high density, the image data corresponding to the area outside the radiation field in the image data for image reproduction is used. A data value corresponding to the low luminance or the high density is assigned to image data.

The radiation image processing apparatus according to the present invention further includes: an irradiation field recognition unit that recognizes the radiation irradiation field based on irradiation field recognition image data representing a radiation image having the radiation irradiation field; The image data for image reproduction corresponding to the region outside the radiation field of the image data for image reproduction, so that the region outside the radiation field of the visible image reproduced based on the image data has low luminance or high density. And a data operation unit for assigning a data value corresponding to the low luminance or the high density.

Here, the “irradiation field recognizing image data” and the “image reproducing image data” may be different image data such as the above-described pre-read image data and pre-read image data, respectively. Good,
For example, when prefetching is not performed, the image data may be the same as each other, such as first recognizing a radiation irradiation field based on the same image data and then reproducing an image based on the image data.

Further, in the present invention, the algorithm for recognizing the radiation field is not limited to a specific one.For example, the radiation field is rectangular in addition to the method described in JP-A-63-259538 described above. As a premise, various methods such as a method of recognizing the rectangular radiation irradiation field can be adopted (Japanese Patent Application Laid-Open No. 61-39039, Japanese Patent Application No. 63-97898).
No., Japanese Patent Application No. 63-250335).

The term “low brightness or high density” refers to low brightness when a visible image is displayed as a brightness distribution on a display screen such as a CRT, and high density when a visible image is reproduced as a density distribution on a film or the like. Say.

(Operation) The radiation image processing method and apparatus of the present invention recognizes a radiation irradiation field, and stores image data corresponding to an area outside the radiation irradiation field such that the area outside the radiation irradiation field of the visible image has low brightness or high density. Because the data value corresponding to the low luminance or high density is assigned to the intense light from the region outside the radiation irradiation field without using a shielding plate or the like when observing the visible image, the visible image is formed. It is possible to obtain a visible image with more excellent suitability for observation without making it difficult to see.

(Embodiment) An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a perspective view showing an example of a radiation image reading apparatus and an embodiment of a radiation image processing apparatus of the present invention.
This system uses a stimulable phosphor sheet and performs pre-reading.

The stimulable phosphor sheet 1 on which one or a plurality of radiation images are recorded is first scanned by a weak light beam to release only a part of the radiation energy accumulated in the sheet 1 and to perform prefetching for prefetching. It is set at a predetermined position of the section 20. The accumulative tendency body sheet 1 set at this predetermined position
Is conveyed (sub-scanning) in the direction of arrow Y by sheet conveying means 3 such as an endless belt driven by a motor 2. On the other hand, the weak light beam 5 emitted from the laser light source 4 is reflected and deflected by the rotating polygon mirror 6 driven by the motor 13 and rotated at high speed in the direction of the arrow, passes through a focusing lens 7 such as an fθ lens, In the direction of the sub-scan (arrow Y direction)
The main scanning is performed in the direction of arrow X, which is substantially vertical. From the portion of the sheet 1 irradiated with the excitation light 5, the stimulated emission light 9 of a light amount corresponding to the accumulated and recorded radiation image information is diverged, and the stimulated emission light 9 is guided by the light guide 10, Photoelectrically detected by a photomultiplier (photomultiplier tube) 11. The light guide 10 is formed by molding a light guide material such as an acrylic plate, and has a linear incident end face 10a.
Are arranged so as to extend along the main scanning line on the stimulable phosphor sheet 1, and the light receiving surface of the photomultiplier 11 is coupled to the emission end face 10b formed in an annular shape. Stimulated luminescence 9 entering the light guide 10 from the incident end face 10a
Travels through the interior of the light guide 10 while repeating total reflection, exits from the exit end face 10b, is received by the photomultiplier 11, and the amount of the stimulating luminescent light 9 carrying the radiation image information is determined by the photomultiplier 11 Is detected by

The analog output signal S output from the photomultiplier 11 is amplified by the amplifier 16 and digitized by the A / D converter 17 to obtain pre-read image data Sp as a digital signal.

In the pre-reading, reading conditions such as a voltage value applied to the photomultiplier 11 and an amplification factor of the amplifier 16 are determined so that the radiation energy stored in the stimulable phosphor sheet 1 can be read over a wide area. ing.

The obtained pre-read image signal Sp is input to the radiation image processing device 40. The radiation image processing apparatus 40 includes a keyboard 41 for inputting various commands and information, a floppy disk drive unit 42 in which a floppy disk as an auxiliary storage medium is mounted and driven, and a display of a visible image based on image data. It comprises a CRT 43, a CPU, an internal memory, and a main unit 44 in which an interface for transmitting and receiving signals to and from the radiation image reading apparatus is built.

The radiation image processing apparatus 40 recognizes the arrangement pattern and the radiation irradiation field of the radiation image recorded on the stimulable phosphor sheet 1 based on the input pre-read image data Sp. The calculation of the radiation field recognition is performed in the main body unit 44. However, the combination of the hardware and software for recognizing the radiation field is considered as an example of the irradiation field recognition unit according to the present invention. .

The radiation image processing apparatus 40 recognizes a radiation irradiation field as follows.

2A to 2C correspond to each of various arrangement patterns of the radiation image recorded on the stimulable phosphor sheet 1 shown in FIG. 1, and the arrangement patterns are represented by binary signals. FIG. 3 is a diagram illustrating an example of a value conversion mask.

In some cases, only one radiation image stored and recorded on one stimulable phosphor sheet 1 is stored and recorded substantially at the center of the sheet 1, but two radiation images are arranged side by side to correspond to FIG. 2A. In some cases, two pieces of data are stored and recorded vertically, as shown in FIG. 2B, and in other cases, four pieces of data are stored and recorded as shown in FIG. 2C. Therefore, based on the pre-read image data Sp, an arrangement pattern of the radiation image is first obtained (see Japanese Patent Application No. 63-35835).

The outer frame 31 in each of FIGS. 2A to 2C corresponds to the entire surface of one stimulable phosphor sheet, and is a region not hatched.
31a indicates an area in which all image signals are "0", and a hatched area 31b indicates an area in which all image signals are "1". The binary masks shown in FIGS. 2A to 2C are stored in advance in the radiation image processing apparatus 40 shown in FIG.

The pre-read image data Sp obtained by the pre-read reading unit 20 shown in FIG. 1 is sent to the radiation image processing device 40 and then binarized to obtain binarized image data. In order to obtain the binarized image data, the average value, the median value, the minimum value, the predetermined value and the maximum value, and the maximum value of the individual pre-read image data Sp respectively corresponding to all the pixels of the stimulable phosphor sheet 1 are calculated. A threshold value such as a value obtained by subtracting a predetermined value from is first obtained, and this threshold value is compared with each pre-read image data Sp. When each pre-read image data Sp is equal to or more than the threshold value, “ It is obtained by setting "1" and "0" in the following cases.

FIG. 3 shows an example of the binarized image data thus obtained.

The outer frame 32 in the figure corresponds to one entire stimulable phosphor sheet similarly to the outer frame 31 in FIGS. 2A to 2C, and the black point 32b indicates the point where the binarized image data is “1”. Shown, other area 32a
Indicates that the binarized image data is “0”.

When the binarized image data is obtained in this manner, the obtained binarized image data is compared with the binarized image data shown in FIGS. 2A to 2C.
Each of the binarization masks is compared, and an evaluation value indicating the degree of pattern matching with each binarization mask is obtained.

As the evaluation value, for example, in the obtained binarized image data (FIG. 3) and each binarized mask (FIG. 2), the signals of the corresponding points on the stimulable phosphor sheet are both The number of points “1” is counted, and this count value is used. Alternatively, the number of points where both are “0” may be counted, and the counted value may be used as an evaluation value. The number of points where both are “1” and the number of points where both are “0” are added. The calculated value may be used as the evaluation value.

After the evaluation value is obtained for the combination of the binarized image data and each of the binarization masks, the maximum evaluation value having the highest degree of pattern matching among the evaluation values is obtained. Thereafter, the maximum evaluation value is compared with a predetermined value indicating a predetermined degree of pattern matching, and the maximum evaluation value is larger than the predetermined value, and the radiation image has a binarization mask arrangement pattern corresponding to the maximum evaluation value. When it is determined that this is the arrangement pattern, the arrangement pattern is recognized, and even if the maximum evaluation value is obtained as described above, it is eventually smaller than the predetermined value, and the radiation image has the binary mask corresponding to this maximum evaluation value. If it cannot be determined that the image is an arrangement pattern, the image is recognized as one radiation image as a whole.

When the arrangement pattern is recognized as described above, each partial area where the radiation image is arranged (for example, when it is recognized that two radiation images are arranged on the left and right shown in FIG. 2A, the stimulable phosphor sheet The radiation field is recognized for each of the left half area and the right half area (see Japanese Patent Application Laid-Open No. 63-259538 described above).

 FIG. 4 is a diagram showing one of the partial areas.

This partial area 33 includes a radiation irradiation field surrounded by a boundary line 34.
A radiation image 36 of the subject is formed in the radiation irradiation field 35.

FIG. 5 shows a number of line segments D ₁ , D ₂ ,..., Dn (for example, 64 lines) extending from the center point 0 of the partial area 33 shown in FIG.
FIG. A boundary point of the radiation field is obtained for each line segment.

FIG. 6 is a diagram showing the pre-read image data Sp shown along a single line segment (for example, D ₁ ) and its difference value ΔSp. At the boundary point of the radiation field, the value of the pre-read image data Sp changes rapidly as shown in FIG. 6 (a), and therefore the difference value ΔP is at the boundary point as shown in FIG. 6 (b). Indicates a peak. By obtaining this peak for each line segment shown in FIG. 5, a large number of boundary points are obtained on the boundary of the radiation irradiation field.

After obtaining the boundary points as described above, if a line along these points is obtained, the line becomes the boundary line of the radiation irradiation field. Lines along these boundary points are, for example, a method of connecting the remaining points after smoothing those points, a method of locally obtaining a plurality of straight lines by applying the least squares method, and a method of connecting them, Although it can be obtained by a method of applying a spline curve or the like, here, the boundary line 34 (see FIG. 4) is obtained by using the Hough transform. Hereinafter, the processing for obtaining this straight line will be described in detail.

When the coordinates of each boundary point obtained as described above are represented as (x ₀ , y ₀ ), a curve represented by ρ = x ₀ cos θ + y ₀ sin θ with these x ₀ and y ₀ as constants , For all boundary points (x ₀ , y ₀ ).

FIG. 7 is a diagram showing some examples of the curve obtained as described above. This curve is the boundary point (x ₀ , y ₀ )
There are as many as.

Next, among a large number of curves corresponding to each boundary point (x ₀ , y ₀ ), an intersection (ρ ₀ ,
θ ₀ ). It is rare that many curves intersect at exactly one point due to an error of the obtained boundary points (x ₀ , y ₀ ). The center of the intersection group is defined as the intersection (ρ ₀ , θ ₀ )
And Next, the intersection (ρ _0, θ ₀₎ obtains a straight line defined by the x-y orthogonal coordinate system _{ρ 0 = x cosθ 0 + y} sinθ 0 from. This straight line extends along a plurality of boundary points (x ₀ , y ₀ ).

Figure 8 is a straight line L ₁ ~L ₅ obtained as described above, FIG. 4 is a diagram showing on the fifth drawing of the same partial region 33.
Since the boundary points are distributed on the boundary line 34 shown in FIG.
As shown in FIG. 8, straight lines L _{1 to} L ₅ extending the boundary line 34
Is required. The region surrounded by these straight lines L _{1 to} L ₅ is recognized as the radiation irradiation field 35.

The irradiation field 35 is recognized, for example, as follows.

It is examined whether the intersection point of the line segment M ₁ ~M ₄ and the straight lines L ₁ ~L ₅ from the center point 0 of the partial region 33 connecting the respective corner of the partial area 33, the intersection point is present case, the straight lines L ₁ ~L ₅
The plane on the side including the corner of the partial region 33 in the plane divided by 2 is truncated. This operation all of the straight line L ₁ ~L ₅
And the line segments M _{1 to} M ₄ , whereby the straight lines L _{1 to} L ₅
Radiation field 35 is required.

When the radiation irradiation field 35 is recognized in this way, the reading conditions at the time of main reading based on the pre-read image signal Sp, that is, the voltage applied to the photomultiplier 11 'of the main reading / reading unit 20' and the amplifier 16 ' Is determined. This reading condition does not consider whether or not the stimulated emission light emitted from the region outside the radiation irradiation field where only the scattered radiation is irradiated without the subject being present is properly read, and from the region within the radiation irradiation. The emitted photostimulated light is determined so that it can be properly read.

After the reading conditions for the main reading are obtained as described above,
The stimulable phosphor sheet 1 'for which pre-reading has been completed is set at a predetermined position of the main reading / reading unit 20' shown in FIG. 1, and the sheet 1 'is scanned by a light beam stronger than the light beam used for the pre-reading, and the image is scanned. A signal is obtained. Here the book reading section
Since the configuration of 20 ′ is substantially the same as the configuration of the pre-reading unit 20, the components corresponding to the components of the pre-reading unit 20 are indicated by the dashes added to the numbers used in the pre-reading unit 20. And a detailed description is omitted.

Photomultiplier 11 'analog output signal S output from the' is 'is amplified by the, A / D converter 17' amplifier 16 are digitized by the image data S _Q is obtained.

The image data _SQ is input to the radiation image processing device 40, and the radiation image processing device 40 appropriately _{adjusts the} image data SQ as necessary so that the image in the radiation irradiation field has excellent observation suitability. image processing is performed, and the data corresponding to the low luminance image data S _Q strong light from the area of the irradiation field corresponding to the region of the irradiation field so as not to interfere with the observation and enters the eyes during observation A value is assigned. This calculation process is also executed in the main body unit 40,
Hardware executing operations assigned a data value corresponding to the low luminance image data S _Q corresponding to the region of the irradiation field, the combination of software is considered that the example of the data operating unit of the present invention.

Suitable image processing if necessary is subjected, and after the data value corresponding to low brightness is assigned to the image data S _Q corresponding to the region of the irradiation field, the image data is CRT43
And a visible image based on the image data is displayed on the CRT 43 for observation.

FIG. 9 is a perspective view showing a CRT 43 for displaying a radiation image recorded in the partial area 33 shown in FIG. 4 as a visible image.

In this visible image, the area 37 outside the irradiation field is displayed with a uniform low brightness, and the light emitted from this area 37 does not enter the eyes and the visible image in the irradiation field 35 does not become difficult to see. .

Although the above embodiment has been described with respect to a system that performs prefetching, a system that does not perform prefetching, that is, first recognizes a radiation irradiation field based on image data obtained by reading, and then generates a visible image based on the image data. The present invention can be applied to a display system and the like.

Although the above embodiment is an example in which a visible image is reproduced and displayed on a CRT, the present invention can be similarly applied to a case where a visible image is reproduced and output on a film using a laser printer or the like.

Further, the present invention can be widely applied not only to the case of using a stimulable phosphor sheet but also to the case of using, for example, an X-ray film.

(Effects of the Invention) As described in detail above, the radiation image processing method and apparatus of the present invention recognizes a radiation irradiation field based on irradiation field recognition image data, and responds to the recognized area outside the radiation irradiation field. Data values corresponding to low brightness or high density are assigned to the image data for image reproduction
Based on the image data obtained in this way, for example, a visible image is reproduced and displayed on a CRT or a visible image is reproduced and recorded on a film. It is not necessary to use a shielding plate or the like that covers the above-mentioned area, and there is no possibility that strong light from an area outside the radiation irradiation field enters the eyes and hinders observation.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a radiation image reading apparatus and an example of a radiation image processing apparatus of the present invention. FIGS. 2A to 2C are views showing examples of various binarization masks. FIG. 3 is a diagram showing an example of the binarized image data, FIG. 4 is a diagram showing one partial area of the stimulable phosphor sheet, and FIG. 5 is a portion shown in FIG. FIG. 6 is a diagram showing a number of line segments extending from the center point of the region to the periphery, FIG. 6 is a diagram showing pre-read image data Sp and A shown along one of the many line segments shown in FIG. The difference value Δ
FIG. 7 is a view showing a method of obtaining a straight line along a boundary point of the obtained radiation irradiation field, and FIG. 8 is a view showing an area surrounded by a straight line along the boundary line. FIGS. 4 and 5 show the same partial area to explain the extraction method. FIG. 9 shows the radiation image recorded in the partial area shown in FIG. 4 as a visible image. FIG. 1 is a perspective view showing a CRT. 1,1 ': stimulable phosphor sheet 2, 2', 13, 13 ': motor 3, 3': sheet conveying means 4, 4 ': laser 6, 6': rotary polygon mirror 9, 9 ': stimulated emission light 11, 11': photomultiplier 20: read-ahead reading unit, 20 ': main reading / reading unit 31, 32: correspond to one entire stimulable phosphor sheet Outer frames 31a, 32a: Area where image signal is "0" 31b ... Area where image signal is "1" 32b ... Point where image signal is "1" 33: Portion of stimulable phosphor sheet Area 34: Boundary of radiation field 35: Radiation field, 36: Subject image 37: Area outside radiation field 40: Radiation image processing device 43: CRT, 44: Main unit

Claims (2)

(57) [Claims] 1. A method of recognizing a radiation field based on image data for recognizing a radiation field representing a radiation image having a radiation field, recognizing the radiation field based on image data for replaying the image representing the radiation image. Data corresponding to the low brightness or high density in the image data for image reproduction corresponding to the area outside the radiation irradiation field in the image data for image reproduction so that the area outside the radiation irradiation field has low luminance or high density. A radiation image processing method comprising assigning values. 2. An irradiation field recognizing unit for recognizing the radiation field based on image data for recognizing a radiation field representing a radiation image having a radiation field, and reproducing the image based on image data for reproducing the image representing the radiation image. The low-brightness or high-density image data for the image reproduction corresponding to the region outside the radiation irradiation field of the image reproduction image data so that the region outside the radiation irradiation field of the obtained visible image has low luminance or high density. A radiation image processing apparatus comprising: a data operation unit that assigns a data value corresponding to a density.