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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a radiation image diagnostic apparatus for reproducing and displaying a radiation image of an object on a display means.
2. Description of the Prior Art
There have heretofore been used methods wherein an object is exposed to radiation such as X-rays to record a radiation image of the object, a radiation image signal representing the radiation image is obtained, various algorithms for image
processing are carried out on the image signal, and the radiation image of the object is reproduced and displayed as a visible image on a display means.
When a stimulable phosphor is exposed to a radiation such as X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays or ultraviolet rays, it stores a part of the energy of the radiation. Then, when the stimulable phosphor which has been
exposed to the radiation is exposed to stimulating rays such as visible light, light is emitted by the stimulable phosphor in proportion to the stored energy of the radiation. As disclosed in U.S. Pat. No. 4,258,264 and Japanese Unexamined Patent
Publication No. 56(1981)-11395, it has been proposed to use a stimulable phosphor in a radiation image recording and reproducing system. Specifically, a sheet provided with a layer of the stimulable phosphor (hereinafter referred to as a stimulable
phosphor sheet) is first exposed to a radiation passing through an object such as the human body to have a radiation image of the object stored thereon, and is then scanned by stimulating rays such as a laser beam which cause the stimulable phosphor
sheet to emit light in proportion to the stored radiation energy. The light emitted by the stimulable phosphor sheet upon stimulation thereof is photoelectrically detected and converted to an electric image signal, image processing is carried out on the
electric image signal, and the radiation image of the object is reproduced as a visible image by use of the processed image signal on a recording medium such as a photographic film, a display means such as a cathode ray tube (CRT), or the like.
In general, with the aforesaid radiation image recording and reproducing system, a single image is displayed at one time in the course of reproducing and displaying the radiation image on the display means such as the CRT display device.
Therefore, in the case where two radiation images are to be compared with each other for the viewing of the condition of progress of a disease, hard copies have heretofore been formed one by one and viewed.
In order to view and compare the hard copies, it is necessary to provide a reproduction means capable of forming the hard copies. In the case where the hard copies are unnecessary in ordinary operations and the reproduction means for the
formation of the hard copies is provided only for the purpose of the viewing and comparison, the equipment cost becomes unnecessarily high. Also, in the case where the reproduction means for the formation of the hard copies is provided, it is often
desired that images be viewed and compared simply even though the hard copies need not be specially formed for comparison. Specifically, comparison of an image related to current viewing, particularly diagnosis, with a past image of the same object as
the object of said image related to current viewing, or with a standard image representing the standard condition of said image related to current viewing.
The term "standard condition" as used herein means, for example, the condition prior to pressing or the standard condition of deformation in the case where the condition of deformation in a specific machine part caused by the pressing is to be
investigated by use of a radiation image, or the condition of a standard appearance of a specific disease in a radiation image in the case where the specific disease of a specific portion of the human body is to be investigated by use of a radiation
image, or a plurality of standard conditions of deformation in respective steps of the aforesaid deformation or a plurality of standard conditions of the disease in respective steps of the aforesaid disease.
In this specification, each group classified in accordance with the machine part, the object portion or the name of disease or the like is referred to as "kind", and a plurality of standard change conditions with respect to the same kind, for
example, a plurality of standard deformation steps of the machine part and steps of progress of the disease are referred to as "steps".
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a radiation image diagnostic apparatus which enables comparison of a radiation image of an object related to current viewing with a past radiation image of the same object without hard
copies being formed.
Another object of the present invention is to provide a radiation image diagnostic apparatus which enables comparison of a radiation image of an object related to current viewing with a standard image representing a standard condition of the
radiation image without hard copies being formed.
The present invention provides a first radiation image diagnostic apparatus comprising:
i) a read-out means for obtaining a radiation image signal representing a radiation image of an object from a recording medium carrying said radiation image of said object recorded thereon,
ii) an ID information input means for entry of ID information on said object,
iii) a storage means for storing past radiation image signals and ID information corresponding to said past radiation image signals,
iv) an image processing means for carrying out image processing of said radiation image signal obtained by said read-out means and of a radiation image signal read from said storage means,
v) a retrieval means for retrieving a single radiation image signal for comparison or a plurality of radiation image signals for comparison, which are of the same object as said object of said radiation image signal related to diagnosis obtained
by said read-out means and which have been obtained before said radiation image signal related to diagnosis is obtained, from said past radiation image signals stored in said storage means on the basis of the ID information entered from said ID
information input means in accordance with said radiation image signal related to diagnosis, and
vi) a display means for reproducing and displaying the radiation image related to diagnosis which said radiation image signal related to diagnosis fed from said read-out means represents and a radiation image for comparison which said radiation
image signal for comparison retrieved by said retrieval means represents, said display means displaying said radiation image related to diagnosis and said radiation image for comparison side by side so that they are viewed simultaneously.
The present invention also provides a second radiation image diagnostic apparatus comprising:
i) a read-out means for obtaining a radiation image signal representing a radiation image of an object from a recording medium carrying said radiation image of said object recorded thereon,
ii) a kind input means for entry of a kind of said object,
iii) a storage means for storing standard image signals obtained from standard images representing standard conditions of radiation images,
iv) an image processing means for carrying out image processing of said radiation image signal obtained by said read-out means,
v) a retrieval means for retrieving a single standard image signal or a plurality of standard image signals corresponding to said radiation image signal, which are stored in said storage means, on the basis of the kind entered from said kind
input means, and
vi) a display means for reproducing and displaying the radiation image which said radiation image signal obtained by said read-out means represents and a standard image which said standard image signal retrieved by said retrieval means
represents, said display means displaying said radiation image and said standard image side by side so that they are viewed simultaneously.
The present invention further provides a third radiation image diagnostic apparatus comprising:
i) a read-out means for obtaining a radiation image signal representing a radiation image of an object from a recording medium carrying said radiation image of said object recorded thereon,
ii) a kind input means for entry of a kind of said object,
iii) a storage means for storing a plurality of standard image signals obtained from standard images representing standard conditions of a plurality of steps of radiation images for each of a plurality of kinds,
iv) a retrieval means for automatically discriminating the step in the kind of said radiation image signal obtained by said read-out means, and retrieving a single standard image signal or a plurality of standard image signals corresponding to
said step of said radiation image signal, which are stored in said storage means, on the basis of the kind entered from said kind input means and said step discriminated automatically, and
v) a display means for reproducing and displaying the radiation image which said radiation image signal obtained by said read-out means represents and a standard image which said standard image signal retrieved by said retrieval means represents,
said display means displaying said radiation image and said standard image side by side so that they are viewed simultaneously.
The present invention still further provides a fourth radiation image diagnostic apparatus comprising:
i) a storage means for storing a radiation image signal obtained from a radiation image of an object and ID information corresponding to said radiation image signal,
ii) a retrieval means for retrieving a single radiation image signal for comparison or a plurality of radiation image signals for comparison, which are stored in said storage means and are of the same object as the object of the radiation image
signal related to diagnosis and which have been obtained before said radiation image signal related to diagnosis is obtained, on the basis of the ID information corresponding to said radiation image signal related to diagnosis stored in said storage
means, and
iii) a display means for reproducing and displaying the radiation image related to diagnosis which said radiation image signal related to diagnosis read from said storage means represents and a radiation image for comparison which said radiation
image signal for comparison retrieved by said retrieval means represents, said display means displaying said radiation image related to diagnosis and said radiation image for comparison side by side so that they are viewed simultaneously.
The present invention also provides a fifth radiation image diagnostic apparatus comprising:
i) a storage means for storing a radiation image signal obtained from a radiation image of an object, a kind corresponding to said radiation image signal, and standard image signals obtained from standard images representing standard conditions
of radiation images,
ii) a retrieval means for retrieving a single standard image signal or a plurality of standard image signals corresponding to said radiation image signal, which are stored in said storage means, on the basis of the kind of said radiation image
signal stored in said storage means, and
iii) a display means for reproducing and displaying the radiation image which said radiation image signal read from said storage means represents and a standard image which said standard image signal retrieved by said retrieval means represents,
said display means displaying said radiation image and said standard image side by side so that they are viewed simultaneously.
The present invention further provides a sixth radiation image diagnostic apparatus comprising:
i) a storage means for storing a radiation image signal obtained from a radiation image of an object, a kind corresponding to said radiation image signal, and a plurality of standard image signals obtained from standard images representing
standard conditions of a plurality of steps of radiation images for each of a plurality of kinds,
ii) a retrieval means for automatically discriminating the step in the kind of said radiation image signal store in said storage means, and retrieving a single standard image signal or a plurality of standard image signals corresponding to said
step of said radiation image signal, which are stored in said storage means, on the basis of the kind of said radiation image signal and said step discriminated automatically, and
iii) a display means for reproducing and displaying the radiation image which said radiation image signal read from said storage means represents and a standard image which said standard image signal retrieved by said retrieval means represents,
said display means displaying said radiation image and said standard image side by side so that they are viewed simultaneously.
With the first and fourth radiation image diagnostic apparatuses in accordance with the present invention provided with the retrieval means for retrieving the past radiation image signal for comparison, which is of the same object as the object
of the radiation image signal related to diagnosis, from a plurality of the past radiation image signals stored in the storage means on the basis of the ID information corresponding to the radiation image signal related to diagnosis, the past radiation
image signal for comparison which is of the same object as the object of the radiation image signal related to diagnosis can be found. Also, with the first and fourth radiation image diagnostic apparatuses wherein the display means reproduces and
displays the radiation image related to diagnosis, which the radiation image signal related to diagnosis represents, and the radiation image for comparison, which the radiation image signal for comparison found in the manner as mentioned above
represents, side by side so that both images are viewed simultaneously, the radiation image related to diagnosis of an object which is to be currently viewed and the past radiation image for comparison of the same object can be compared with each other
for investigating a change with the passage of time or the like without hard copies being formed.
Furthermore, with the first radiation image diagnostic apparatus in accordance with the present invention provided with the image processing means, the radiation image related to diagnosis and the radiation image for comparison can be
appropriately image-processed for facilitating the comparison.
With the second and fifth radiation image diagnostic apparatuses in accordance with the present invention provided with the retrieval means for retrieving a single standard image signal or a plurality of standard image signals corresponding to
the radiation image signal related to diagnosis from the standard image signals stored in the storage means on the basis of the kind entered from the kind input means or the kind of the radiation image signal stored in the storage means, the standard
image signal of the same kind as the radiation image signal can be found. Also, with the second and fifth radiation image diagnostic apparatuses in accordance with the present invention wherein the display means reproduces and displays the radiation
image, which the radiation image signal represents, and the standard image, which the standard image signal represents, side by side so that both images are viewed simultaneously, the radiation image which is to be currently viewed and the standard image
representing the standard condition of the radiation image can be compared with each other to investigate, for example, the extent of difference of the radiation image from the standard image, and the step to which the radiation image belongs.
With the third and sixth radiation image diagnostic apparatuses in accordance with the present invention, the storage means stores a plurality of the standard image signals obtained from the standard images representing standard conditions of a
plurality of steps of radiation images for each of a plurality of kinds. Also, in this case, the retrieval means automatically discriminates the step in the kind of the radiation image signal related to diagnosis, and retrieves a single standard image
signal or a plurality of standard image signals corresponding to the radiation image signal related to diagnosis from the standard image signals stored in the storage means on the basis of the kind of the radiation image signal and the step discriminated
automatically. Also, as with the second and fifth radiation image diagnostic apparatuses in accordance with the present invention, the display means reproduces and displays the radiation image and the standard image side by side so that they are viewed
simultaneously. Therefore, the radiation image which is to be viewed currently and the standard image obtained in the manner as mentioned above and representing the same step as the step of the radiation image or two standard images representing two
steps in the case where the radiation image belongs to the middle between the two steps can be compared with each other for investigating a different of the radiation image from the standard image, such as a specific feature of the radiation image which
the standard image does not have, without hard copies being formed.
With the aforesaid second and fifth radiation image diagnostic apparatuses in accordance with the present invention, in the case where each kind includes a plurality of the steps and the standard image signal is present for each of a plurality of
the steps, the viewer has to judge the step to which the radiation image belongs by comparing the radiation image with a plurality of the standard images obtained by the retrieval means. On the other hand, with the third and sixth radiation image
diagnostic apparatuses in accordance with the present invention wherein the retrieval means is provided with the function of automatically recognizing the step in each kind of the radiation image signal, the standard image signal approximate to the
radiation image signal can be obtained automatically. Therefore, the viewer need not carry out the troublesome judgment, and the diagnosis time can be shortened.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing an embodiment of the first radiation image diagnostic apparatus in accordance with the present invention,
FIG. 2 is a perspective view showing an example of the read-out means and an example of the ID information input means,
FIGS. 3A, 3B and 3C are perspective views showing examples of the display means,
FIG. 4A is a block diagram showing an embodiment of the second radiation image diagnostic apparatus in accordance with the present invention,
FIG. 4B is a block diagram showing an embodiment of the third radiation image diagnostic apparatus in accordance with the present invention,
FIG. 5 is a block diagram showing an embodiment of the fourth radiation image diagnostic apparatus in accordance with the present invention,
FIG. 6 is a perspective view showing an example of the radiation image recording and read-out apparatus for obtaining the radiation image signal and ID information,
FIG. 7A is a block diagram showing an embodiment of the fifth radiation image diagnostic apparatus in accordance with the present invention, and
FIG. 7B is a block diagram showing an embodiment of the sixth radiation image diagnostic apparatus in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will hereinbelow be described in further detail with reference to the accompanying drawings.
With reference to FIG. 1 showing an embodiment of the first radiation image diagnostic apparatus in accordance with the present invention, a radiation image signal S1 representing a radiation image of an object is obtained by a read-out means 1
as will be described later from a recording medium carrying the radiation image recorded thereon. The radiation image signal S1 obtained is a radiation image signal related to diagnosis which is to be viewed currently. The radiation image signal S1
related to diagnosis is fed to an image processing means 2 which carries out image processing appropriately in accordance with the radiation image signal, and the image-processed radiation image signal S1' related to diagnosis is sent to a display means
3. Also, for comparison with a radiation image signal obtained thereafter by the read-out means 1, the radiation image signal S1 related to diagnosis is sent to a storage means and stored therein together with ID information S2 as will be described
later.
The ID information S2 of the object corresponding to the radiation image signal S1 related to diagnosis obtained by the read-out means 1 is entered from an ID information input means 4 to a retrieval means 5. In the case where this embodiment is
used for diagnosis of a disease of the human body by way of example, the term "ID information S2" as used herein means the name of the patient, the date of image recording, the image recording portion and other information specifying the object. The ID
information S2 is also sent to the storage means 6 and stored therein together with the radiation image signal S1 related to diagnosis as mentioned above.
The storage means 6 stores a plurality of radiation image signals of a plurality of objects read out by the read-out means 1 in the past and the ID information entered from the ID information input means 4 in accordance with the respective
radiation image signals. A plurality of the radiation image signals and the ID information stored in the storage means 6 are not limited to the radiation image signals obtained by the read-out means 1 and the ID information entered from the ID
information input means 4, and may be obtained from other read-out means or the like and stored in the storage means 6 via a magnetic disk, a magnetic tape or the like.
Upon receiving the ID information S2 from the ID information input means 4, the retrieval means 5 retrieves a single radiation image signal S3 for comparison or a plurality of radiation image signals S3, S3, . . . for comparison, which are of
the same object as the object of the radiation image signal S1 related to diagnosis read out by the read-out means 1, from a plurality of the past radiation image signals stored in the storage means 6 on the basis of the I information S2.
The single radiation image signal S3 for comparison or a plurality of the radiation image signals S3, S3, . . . for comparison thus retrieved are subjected to necessary image processing in the image processing means 2. The single
image-processed radiation image signal S3' for comparison or a plurality of the image-processed radiation image signals S3', S3', . . . for comparison are sent to the display means 3 together with the image-processed radiation image signal S1' related
to diagnosis. On the basis of the radiation image signal S1' related to diagnosis and the radiation image signal S3' for comparison, the display means 3 reproduces and displays a radiation image related to diagnosis and a radiation image for comparison
side by side so that they can be viewed simultaneously as will be described later.
FIG. 2 shows an example of the read-out means 1 and an example of the ID information input means 4.
The read-out means 1 shown in FIG. 2 utilizes a stimulable phosphor sheet.
With reference to FIG. 2, a stimulable phosphor sheet 11 carrying a radiation image of an object stored thereon is conveyed in a sub-scanning direction as indicated by the arrow Y by a sheet conveyance means 13 constituted by an endless belt or
the like operated by a motor 12. On the other hand, stimulating rays 15 produced by a laser beam source 14 are reflected and deflected by a rotating polygon mirror 16 quickly rotated in the direction as indicated by the arrow, and pass through a
converging lens 17 constituted by a f.theta. lens or the like. The optical path of the stimulating rays 15 is then changed by a mirror 18, and the stimulating rays 15 impinge upon the stimulable phosphor sheet 11 and scan it in a main scanning
direction as indicated by the arrow X approximately normal to the sub-scanning direction as indicated by the arrow Y. As the stimulable phosphor sheet 11 is exposed to the stimulating rays 15, the exposed portion of the stimulable phosphor sheet 11 emits
light 19 in an optical amount proportional to the stored radiation energy. The emitted light 19 is guided by a light guide member 20, and photoelectrically detected by a photomultiplier 21 as a photodetector. The light guide member 20 is made by the
forming of a light guiding material such as an acrylic plate, and has a linear light input face 20a positioned to extend along the main scanning line on the stimulable phosphor sheet 11, and a ring-shaped light output face 20b closely contacted with a
light receiving face of the photomultiplier 21. The emitted light 19 entering the light guide member 20 from its light input face 20a is guided through total reflection inside of the light guide member 20, emanates from the light output face 20b, and is
received by the photomultiplier 21. In this manner, the amount of the emitted light 19 carrying the radiation image is detected by the photomultiplier 21.
An analog signal S generated by the photomultiplier 21 is amplified by an amplifier 22, and digitized by an A/D converter 23 with a predetermined scale factor. The signal thus digitized is fed as the radiation image signal S1 related to
diagnosis into the image processing means 2 as mentioned above.
The read-out means 1 is not limited to the apparatus using the stimulable phosphor sheet and may, for example, be an apparatus for reading out an image signal representing an X-ray image by scanning a conventional X-ray photographic film carrying
the X-ray image recorded thereon. Alternatively, the read-out means 1 may be an apparatus for reading out an image signal from a film on which an output image generated by a diagnosis device such as a CT scanner or US is recorded.
Before or after the radiation image is read out from the stimulable phosphor sheet 11 shown in FIG. 2, the ID information S2 on the object whose radiation image has been stored on the stimulable phosphor sheet 11 is entered from a keyboard 24
constituting the ID information input means 4. As mentioned above, the ID information S2 is sent to the retrieval means 5 and the storage means 6.
Examples of the display means 3 will be described hereinbelow with reference to FIGS. 3A, 3B and 3C. In FIGS. 3A, 3B and 3C, for simplicity of explanation, the symbols S1' and S3' denoting the image signals are used also for denoting the images.
With reference to FIG. 3A, a radiation image S1' related to diagnosis which the radiation image signal S1' related to diagnosis represents and a radiation image S3' for comparison which the radiation image signal S3' for comparison represents are
displayed side by side on a single CRT display device. In the case where a plurality of radiation images S3', S3', . . . for comparison are to be displayed, they may be made small and displayed side by side simultaneously together with the radiation
image S1' related to diagnosis on the single CRT display. In the case where the images should not be made too small, the radiation image S1' related to diagnosis may be displayed continuously, and a plurality of the radiation images S3', S3', . . . for
comparison may be sequentially displayed one after another. In this case, a radiation image S3' for comparison closest to the date of image recording of the radiation image S1' related to diagnosis among a plurality of the radiation images S3', S3', .
. . for comparison should preferably be displayed first, and thereafter the radiation images S3', S3', . . . for comparison prior to said radiation image S3' for comparison should be displayed retrospectively one after another, thereby to facilitate
investigation of a change with the passage of time between the radiation image S1' related to diagnosis and the radiation images S3', S3', . . . for comparison.
In the example shown in FIG. 3B, the radiation image S1' related to diagnosis is displayed on one of the two CRT display devices, and the radiation image S3' for comparison is displayed on the other of the CRT display devices. In the case where
a plurality of the radiation images S3', S3', . . . for comparison are to be displayed, a plurality of the images may be displayed on each CRT display device as in the example shown in FIG. 3A, or the radiation images S3', S3', . . . for comparison may
be displayed one after another.
In the example shown in FIG. 3C, three CRT display devices are provided side by side. In the case where only a single radiation image S3' for comparison is to be displayed, only two among the three CRT display devices may be used. In the case
where a plurality of the radiation images S3', S3', . . . for comparison are to be displayed, the radiation images S3', S3', . . . for comparison in a number (two in this example) capable of being displayed simultaneously with the radiation image S1'
related to diagnosis on the display means are displayed at the same time as the radiation image S1' related to diagnosis. In this case, in order to investigate the latest change, the radiation images S3', S3', . . . for comparison should preferably be
displayed retrospectively from the image recorded most lately to the previous images. In the case where there are some radiation images S3', S3', . . . for comparison which cannot be displayed simultaneously, the images may be displayed one after
another.
The number of the CRT display devices constituting the display means is not limited to one, two or three as shown in FIG. 3A, FIG. 3B or FIG. 3C, and the display means is not limited to the CRT display device.
An embodiment of the second radiation image diagnostic apparatus in accordance with the present invention will hereinbelow be described with reference to FIG. 4A. In FIG. 4A, similar elements are numbered with the same reference numerals with
respect to FIG. 1 (this applies also to the subsequent drawings).
With reference to FIG. 4A the radiation image signal S1 obtained by the read-out means 1 as shown in FIG. 2 is the radiation image signal related to diagnosis which is to be viewed currently. The radiation image signal S1 is fed to the image
processing means 2 which carries out image processing appropriately in accordance with the radiation image signal, and the image-processed radiation image signal S1' is sent to the display means 3.
Information S4 on the kind of the object corresponding to the radiation image signal S1 obtained by the read-out means 1 is entered from a kind input means 34 to a retrieval means 35. In the case where this embodiment is used for diagnosis of a
disease of the human body by way of example, the term "kind information S4" as used herein means the image recording portion of the human body, the name of disease and other information specifying the group to which the object belongs. Also, radiation
image signals representing standard appearances of various diseases in radiation images and radiation image signals representing typical radiation images or the like in various steps of progress of a specific disease are selected based on long experience
from a plurality of the radiation image signals obtained by, for example, the read-out means 1, and are stored as standard image signals in the storage means 36. The standard image signals stored in the storage means 36 are not limited to the radiation
image signals obtained by the read-out means 1, and may be obtained from other read-out means or the like and stored in the storage means 36 via a magnetic disk, a magnetic tape or the like. In the case where already-formed standard images are
available, the standard image signals may be obtained by reading out the standard images by use of a digitizer or the like, instead of selecting the standard image signals from a plurality of the radiation image signals as mentioned above.
Upon receiving the kind information S4 from the kind input means 34, the retrieval means 35 retrieves a single standard image signal S5 or a plurality of standard image signals S5, S5, . . . , which correspond to the radiation image signal S1
related to diagnosis read out by the read-out means 1, from a plurality of the standard image signals stored in the storage means 36 on the basis of the kind information S4.
The single standard image signal S5 or a plurality of the standard image signals S5, S5, . . . thus retrieved are subjected to image processing in the image processing means 2 when necessary. The single standard image signal S5' or a plurality
of the standard image signals S5', S5', . . . passing through the image processing means 2 are sent to the display means 3. On the basis of the radiation image signal S1' and the standard image signal S5', the display means 3 reproduces and displays a
radiation image and a standard image side by side so that they can be viewed simultaneously as will be described later.
An embodiment of the third radiation image diagnostic apparatus in accordance with the present invention will hereinbelow be described with reference to FIG. 4B. In FIG. 4B, similar elements are numbered with the same reference numerals with
respect to FIG. 4A.
The radiation image signal S1 obtained by the read-out means 1 is subjected to appropriate image processing in the image processing means 2, and then sent to the display means 3 and a retrieval means 35'. Based on the kind information S4 entered
from the kind input means 34 and the radiation image signal S1, the retrieval means 35' automatically discriminates the step in the kind of the radiation image signal S1 by, for example, the method as will be described later. Thereafter, based on the
kind of the radiation image signal S1 and the step discriminated automatically, the retrieval means 35' retrieves a single standard image signal S5 or a plurality of standard image signals S5, S5, . . . corresponding to the step of the radiation image
signal S1 from a plurality of standard image signals stored in the storage means 36. The term "single standard image signal S5" as used herein means, for example, the standard image signal S5 in the same step as the step to which the radiation image
signal S1 belongs, and the term "plurality of standard image signals S5, S5, . . . " means, for example, the standard image signals S5, S5 in two steps in the case where the radiation image signal S1 belongs to the middle between the two steps.
As in the second radiation image diagnostic apparatus in accordance with the present invention, the single standard image signal S5 or a plurality of the standard image signals S5, S5, . . . thus retrieved are sent to the display means 3 via the
image processing means 2. The display means 3 reproduces and displays the radiation image and the standard image side by side so that they can be viewed simultaneously.
The method of automatically discriminating the step in the kind of the radiation image signal S1 in the retrieval means 35' will be described hereinbelow.
Any known method may be used as the method of automatic discrimination. A example of the method wherein a radiation image of pneumoconiosis is taken as one kind and a step in said kind is automatically discriminated will be briefly described
below.
Pneumoconiosis includes symptoms such as shortness of breath and hard breath caused by dust inhaled and clinging to the lungs, and exhibits spot-like affected portions in a radiation image of the lungs. A plurality of standard steps are defined
in accordance with the number of spots or the like related to the extent of the disease.
As the method of automatically discriminating the step of the pneumoconiosis radiation image, it is possible to employ a method utilizing a simultaneous occurrence matrix as described in "IEEE TRANSACTIONS SYSTEMS, MAN, AND CYBERNETICS", SMC-4,
pp. 40-49, 1974, a method utilizing a mean density change in an extracted region as described in "IEEE TRANSACTIONS ON COMPUTERS", C-25, pp. 95-97, 1976, and a method based on linear prediction as described in "IYODENSHI TO SEITAIKOGAKU" (Medical
Electronics and Biology), Vol. 20, No. 5, Sept. 1982. The method utilizing the simultaneous occurrence matrix will be described below.
First, the simultaneous occurrence matrix expressed as
is calculated for overall image signals inside of the lungs. In Formula (1), i and j each denote the density level and attains a value within the range of 0 to 7 (the overall density region is classified into eight levels). Also, a denotes the
direction (angle) of a picture element at which the density level is equal to j, as viewed from a picture element at which the density level is equal to i, and picture elements present in the directions of 0.degree., 45.degree., 90.degree. and
135.degree. are employed. Furthermore, d denotes the distance from the picture element at which the density level is equal to i to the picture element at which the density level is equal to j, and picture elements at distances of 1, 3, 7 and 11 are
employed.
Thereafter, based on the simultaneous occurrence matrix p(i,j,a,d) calculated in the manner as mentioned above, five reference amounts T1 (a,d) to T5 (a,d) are calculated as represented by formulas ##EQU1##
On the basis of T1 (a,d) to T5(a,d) thus calculated, a mean value Mk(d), a range Rk(d) and a variance Vk(d) where k=1, 2, . . . , 5 are calculated as represented by formulas ##EQU2##
In the aforesaid formulas, k=1, 2, . . . , 5, and values of a=1, 2, 3 and 4 are made to correspond to the directions of 0.degree., 45.degree., 90.degree. and 135.degree. respectively.
As for 60 reference amounts in total of formulas (7), (8) and (9) or some reference amounts determined from among these reference amounts, values are calculated in accordance with the calculation formulas shown above. The values thus calculated
are compared with values of reference amounts classified in advance for each step on the basis of many pneumoconiosis images, and the step to which the pneumoconiosis image related to diagnosis belongs is discriminated. By way of example, in the case of
classification into four steps, the reference amounts of R4(3), M5(1), R5(7), V4(3), M5(e), V5(3) and M1(3) are used.
After the step of the pneumoconiosis radiation image is automatically discriminated by carrying out the aforesaid operations in the retrieval means 35', the standard image signal corresponding to said step is read from the storage means 36 and
sent to the display means 3, and the standard image is reproduced and displayed together with the pneumoconiosis radiation image on the display means 3.
As the standard image and the radiation image in the steps corresponding to each other are reproduced and displayed together, it is possible to compare both images with each other and to investigate the presence or absence of a condition inherent
to a pneumoconiosis patient which does not appear in the standard image, the lightness or heaviness of the disease in the same steps as compared with the standard image, or the closeness to one of the standard images in two steps in the case where the
radiation image belongs to the middle between the two steps.
In the case of the embodiment shown in FIG. 4A, before or after the radiation image is read out from the stimulable phosphor sheet 11 as shown in FIG. 2, the kind information S4 on the object whose radiation image has been stored on the
stimulable phosphor sheet 11 is entered from the keyboard 24 constituting the kind input means 34 to the retrieval means 35.
Examples of the display means 3 in the embodiments shown in FIGS. 4A and 4B will be described hereinbelow with reference to FIGS. 3A, 3B and 3C. In FIGS. 3A, 3B and 3C, for simplicity of explanation, the symbols S1' and S5' denoting the image
signals are used also for denoting the images.
With reference to FIG. 3A, the radiation image S1' which the radiation image signal S1' represents and a standard image S5' which the standard image signal S5' represents are displayed side by side on a single CRT display device. In the case
where a plurality of standard images S5', S5', . . . are to be displayed, they may be made small and displayed side by side simultaneously together with the radiation image S1' on the single CRT display. In the case where the images should not be made
too small, the radiation image S1' may be displayed continuously, and a plurality of the standard images S5', S5', . . . may be sequentially displayed one after another. In this case, a standard image S5' corresponding to the step present at an end
when a plurality of the standard images S5', S5', . . . are arranged side by side in the sequence of the steps should preferably be displayed first, and thereafter the standard images S5', S5', . . . in the adjacent steps should be displayed one after
another, thereby to facilitate investigation of the standard image S5' to which the radiation image S1' is approximate.
In the example shown in FIG. 3B, the radiation image S1' is displayed on one of the two CRT display devices, and the standard image S5' is displayed on the other of the CRT display devices. In the case where a plurality of the standard images
S5', S5', . . . are to be displayed, a plurality of the images may be displayed on each CRT display device as in the example shown in FIG. 3A, or the standard images S5', S5', . . . may be displayed one after another.
In the example shown in FIG. 3C, three CRT display devices are provided side by side. In the case where only a single standard image S5' is to be displayed, only two among the three CRT display devices may be used. In the case where a plurality
of the standard images S5', S5', . . . are to be displayed, the standard images S5', S5', . . . in a number (two in this example) capable of being displayed simultaneously with the radiation image S1' on the display means are displayed at the same time
as the radiation image S1'. In this case, the standard images S5', S5', . . . | | |
