JPS6290137A - Method and apparatus for forming arbitrary tomographic image - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a method for forming an arbitrary tomographic image of a subject such as a human body. A method for forming an arbitrary tomographic image, in which simultaneous multilayer tomography is performed using body sheets, and an arbitrary tomographic image is formed using image signals read from these stimulable phosphor sheets, and this method. It relates to an apparatus for carrying out the process.

(Technical Background of the Invention and Prior Art) Radiographic M@shape imaging has been known as a method of obtaining a tomographic image of a desired tomographic plane of a subject such as a human body. In this method, a radiation source such as an The focal point of the plane, one point on the tomographic plane, and one point on the radiation film form a straight line) and the law of geometric ratios (the ratio of the distance between the focal point and the tomographic plane and the distance between the tomographic plane and the film is constant) ), only the desired tomographic plane is visualized on the radiographic film, and the tomographic planes of other subjects are blurred, and as a result, only the desired tomographic plane of the subject is imaged. A teaching line image is obtained.

Furthermore, so-called simultaneous multilayer tomography is also known, in which multiple pieces of radiographic film are stacked and the same imaging as described above is performed to obtain multiple different tomographic images of the subject at once (simultaneously). . In addition, in such a cross-section M projection method, it is sufficient that the above-mentioned straight line law and geometric ratio law hold, and the movement method of the radiation source and radiographic film is linear,
Any method such as circular, elliptical, or spiral may be used.

Furthermore, in the above-mentioned simultaneous multilayer tomography method, the applicant has already proposed a method in which a high-sensitivity stimulable phosphor sheet is used in place of the photographic film to reduce the radiation exposure of the subject during radiography. (For example, Japanese Patent Application Laid-Open No. 1983-
No. 67245) a, that is, X-rays, α
When irradiated with radiation such as rays, β-rays, T-rays, ultraviolet rays, or electron beams, part of the energy of this radiation is accumulated in the phosphor, and then the phosphor is irradiated with excitation light such as visible light. Then, the phosphor emits fluorescence (stimulated luminescence) depending on the accumulated energy. A phosphor exhibiting such properties is called a stimulable phosphor (stimulable phosphor), and a stimulable phosphor sheet is a sheet-like recording medium made of the above-mentioned stimulable phosphor. It generally consists of a support and a stimulable phosphor layer laminated on the support. The stimulable phosphor layer is formed by dispersing a stimulable phosphor in a suitable binder.
If the stimulable phosphor layer is self-supporting, it will stand on its own as a stimulable phosphor sheet. Regarding such a stimulable phosphor sheet, for example, Japanese Patent Application Laid-Open No. 855-124
No. 29, No. 55-116340, No. 55-16347
2, No. 56-11395, No. 56-104645, and the like.

Once a tomographic image of a subject has been stored and recorded on a plurality of laminated stimulable phosphor sheets as described above, each of these stimulable phosphor sheets is irradiated with excitation light such as visible light to make it shine. If the stimulated luminescent light is emitted and the stimulated luminescent light is read photoelectrically, an electrical image signal representing a tomographic image is obtained. Using the image signal obtained in this way, the tomographic image can be displayed on a display such as a CRT, or it can be permanently recorded as a hard copy using an optical scanning recording device or the like.

However, even if the stimulable phosphor sheet described above or the radiographic film described above is used, the amount of information recorded by conventional simultaneous multilayer tomography is limited. These are tomographic images of several tomographic planes. Therefore, even if the photographic film is developed or the tomographic images are reproduced by reading the stored information on the stimulable phosphor sheet, no knowledge can be obtained about the areas between the tomographic images.

(Object of the Invention) The present invention has been made in view of the above circumstances, and provides an arbitrary tomographic image forming method capable of forming an arbitrary tomographic image of a subject, and an apparatus for executing the method. It is intended for that purpose.

(Structure of the Invention) The method for forming an arbitrary tomographic image of the present invention is based on the fact that by using the stimulable phosphor sheet described above, radiation image information of a subject can be obtained as an electrical image signal. As described above, different tomographic images of the subject are stored and recorded on this stack of stimulable phosphor sheets, and then each of these stimulable phosphor sheets is extracted as described above. Image signals each representing a tomographic image are obtained, and at least two sets of image signals among the plurality of sets of image signals obtained in this way are added weighted () between the signals for corresponding pixels, and the obtained image is obtained by this addition. The present invention is characterized in that the added signal is input to an image reproducing device, and a tomographic image is formed based on the added signal.

The arbitrary tomographic image forming apparatus of the present invention capable of carrying out the above method includes an image recording section that accumulates and records different tomographic images of a subject on a plurality of stacked stimulable phosphor sheets as described above; The excitation light is applied to each of the sheets, thereby detecting the stimulated luminescence light emitted from the sheet, and each F! an image reading unit that reads a plurality of sets of image signals representing the iI layer image; a tomographic plane specifying means for specifying an arbitrary tomographic plane; a weighted addition unit that determines a weighting coefficient of an image and adds weights between corresponding pixels according to the weighting coefficient of at least two sets of image signals read from the storage means; It must be characterized by being composed of.

(Function) As described above, by weighting and adding the image signals carrying different tomographic images, it is possible to form a tomographic image at an intermediate position between the tomographic images carried by each signal.
By changing the weighting, it is possible to form a tomographic image of any tomographic plane at the intermediate position.

(Embodiments) Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 shows an image recording section 1 which forms a part of the apparatus of the present invention and performs simultaneous multilayer tomography using a stimulable phosphor sheet. Emit radiation so as to face the radiation source 10 such as an X-ray tube! ) A set of cassettes 11 for recording image information is arranged, and between this cassette 11 and the radiation source 10,
A subject (human body) 12 as a subject is placed. For example, ten stimulable phosphor sheets A1 to AIO are stored in the cassette 11 in a stacked manner. These stimulable phosphor sheets 81 to A10 are as described above.

When taking a tomographic image of a subject 12, radiation 13 is irradiated from a radiation source 10 through the subject 12 to a stimulable phosphor sheet in a cassette 11 in the directions 1 to Δ10. At this time, the radiation source 10 is moved in the direction of arrow 14 in FIG. 1, and at the same time, the cassette 11 is also moved in the direction of arrow 15. In this case, the radiation source 10 and the cassette 11 are connected to the stimulable phosphor sheets 1 to AIO and the radiation source 10 according to the above-mentioned straight line rule and geometric ratio rule, respectively, regarding the 10 layers of tomographic planes 81 to 810 of the subject 12. and will be moved to satisfy. In other words, regarding the fault plane 3n (n-1, 2...1
0), the stimulable phosphor sheet An and the fi radiation source 10 satisfy the straight line law and the geometric law.

By performing radiography in this manner, only the tomographic plane Bn is imaged on the stimulable phosphor sheets 1 to An.
A line of sight image with other parts blurred is stored and recorded. In this way, in simultaneous multilayer tomography using the stimulable phosphor sheets A1 to AIO, the sheet A described later
By changing the reading gain for each stimulable phosphor sheet when reading radiation image information from sheets A1 to A10, the sensitivity of each sheet A1 to A10 can be corrected.
Unlike when using conventional X-ray film, there is no need to use an intensifying screen to set the lower layer to have a high sensitivity. Furthermore, since the stimulable phosphors C1-A1 to AIO have higher sensitivity than the above-mentioned X-ray film, it is possible to simultaneously capture a much larger number of rejected images than when using X-ray film. .

The stimulable phosphor sheet A1~ on which the tomographic images for each of the tomographic planes 81~1310 are accumulated and recorded as described above.
The AIO is then subjected to radiation image information reading in the image reading section 2 shown in FIG.

First, the stimulable phosphor sheet A1 is conveyed in the direction of arrow Y for sub-scanning by a sheet conveying means 21 such as an endless belt. Further, the laser beam 23 as excitation light emitted from the laser light source 22 is deflected by an optical deflector 24 such as a galvanometer mirror, and the stimulable phosphor sheet A1 is directed in the direction of the arrow X, which is substantially perpendicular to the sub-scanning direction Y. Main scan. Stimulated luminescent light 25 is emitted from the portion of the sheet A1 irradiated with the laser beam 23 in an amount corresponding to the radiation image information stored and recorded, and this stimulated luminescent light 25 is collected by the condenser 26. The light is emitted and is photoelectrically detected by a photomultiplier (photomultiplier tube) 27 as a photodetector.

The light condenser 26 is made by molding a light guide material such as an acrylic plate, and has an incident end surface 26a having a straight or glandular shape.
is arranged so as to extend along the beam scanning line on the stimulable phosphor sheet A1, and is formed in an annular shape.
The light-receiving surface of the photomultiplier 27 is coupled to the photomultiplier 27. The stimulated luminescent light 25 entering the light condenser 26 from the incident end surface 26a travels through the light condensing body 26 through repeated total reflection, exits from the output end surface 26b, and is received by the photomultiplier 27. , the amount of light of the stimulated luminescence light 25 carrying the radiation image information is determined by this photomultiplier? 7. The preferred shape, material, and manufacturing method of the light condenser 26 are described in detail in, for example, US Pat. No. 4,346,295.

The output signal (read image signal) So of the photomultiplier 27 is amplified by the log amplifier 28 and digitized by the A/D converter 29. In this way, a digital read image signal $1 representing a tomographic image of the tomographic plane B1 is output from the stimulable phosphor sheet A1. file E].

In the same manner as described above, the other stimulable phosphor sheets A2 to AIO are also subjected to image reading, and each sheet A2
-AIOs obtain digital read image signals 82-310 representing tomographic images of tomographic planes 82-B10, respectively. These read image signals 82 to S10 are respectively stored in image files E2 to F1G similar to the image file F1.

FIG. 3 shows that based on the read image signals 81 to 310,
This figure shows a part of the apparatus of the present invention, which forms an arbitrary tomographic image between the tomographic planes 81 to 1310 of the subject 12. In this device, a weighted addition unit 30 and a tomographic plane designation unit 31
consists of a known computer.

The addition signal Sa output from the weighted addition section 30 is
The image is input through the image processing section 32 to a display 33 such as a CRT. The tomographic plane specifying section 31 has an input knob 35 combined with the display 33, as shown in FIG. 4 as an example. By rotating this input knob 35, the tomographic planes B1 and 3 of the subject 12 are
A tomographic plane designation signal 3s indicating an arbitrary IgI layer plane between 10
is input to the weighted addition section 30. Note that the arbitrary tomographic plane specified in this way is the tomographic plane 8 of the 10 layers.
In addition to 1 to B10, it is possible to specify in sufficient detail, for example, about 10 layers between two adjacent fault planes 3n and 3m (m - mouth + 1) (in this example, 1 to B10).
00E=10+9x10F tomographic plane can be specified>. The tomographic plane designation signal Ss is also sent to the display control section 34. This display control section 34 controls the display 33
Marks M1~ indicating the tomographic planes 81~310 of the above 10 layers
Fixed display of M10 and fault plane designation section @SS
Display the cursor C that moves between the marks M1 to MIO according to pA to see which tomographic plane is specified.
Make it possible to do WX.

The weighted addition section 30 receives the tomographic plane designation signal 3s, and performs the following weighted addition according to the tomographic plane designation signal SS. That is, as shown in FIG. 5, if the tomographic plane 3x indicated by the tomographic plane designation signal SS is necessarily between the tomographic planes 3n and Bm, then you have found it! >l] The tightening unit 30 extracts tomographic planes [3n and 3 from the image files F1 to F10.
Read out image signals SO and 3m for m. Then, the distance between the fault plane 3n and the layer plane [3m is D, the distance from the fault plane Bn to the fault plane Bx is d, and therefore the distance from the fault plane [3x to the fault plane [3m] is (D-d). Then, between the corresponding pixel signals of the image signal 3n and Sm, Sa=((D-d)Sn+63m)/D-(
1) A weighted h0 calculation is performed to obtain the addition signal S88. As is clear from the above, this addition signal 3a indicates the tomographic image (assumed image) at 45 on the designated tomographic plane Bx. As described above, this addition signal 3a is input to the image processing section 32, where it is subjected to processing such as gradation processing and frequency processing, and then input to the display 33. to be displayed.

By operating the input knob 35 as described above, tomographic plane B
If an arbitrary tomographic plane 3x between 1 and 310 is designated, a tomographic image of this arbitrary tomographic plane BX will be displayed on the display 33+. If the weighted addition process of the i:C':J addition section 30 is performed at a sufficiently high speed,
By slowly turning the input knob 35 in a continuous manner, a tomographic image that changes moment by moment from the tomographic plane B1 toward Shifu plane [310] or in the opposite direction is displayed, and the It also becomes possible to understand 12 three-dimensionally.

Note that the image reproducing device that forms a tomographic image of an arbitrary tomographic plane 13x based on the addition signal Sa is not limited to the display 33 such as the CRT, but may also be an optical scanning device that forms a hard copy of the tomographic image. A recording device, etc. may also be used. However, the display 33 such as a CRT is particularly suitable and necessary because it can display a tomographic image by continuously changing the cross-section as described above. Furthermore, the means for inputting the designated viTT layer surface [3x is not limited to the input knob 35 mentioned above.
Other devices such as a mouse, keyboard, touch sensor, etc. may also be used.

Roughly speaking, in the embodiment described above, the tomographic plane 81
It is also possible to form a tomographic image of an arbitrary cross-sectional plane Bx parallel to the tomographic planes 81 to B10, or to form a tomographic image of an arbitrary tomographic plane oblique to the tomographic planes 81 to B10. In other words, as shown in Fig. 6, the oblique designated fault plane [3x is 2
If the cross section (3) plane Bn is between 3 m, the value of d is set to dl according to the position of each pixel in the designated tomographic plane Bx in the above equation (1).

It is only necessary to perform weighted addition by changing the value from dl to dl. In addition, as shown in Figure 7, if the designated oblique fault plane Bx is between three or more fault planes, the value of d in equation (1) is changed as described above, and the The image signal Sn, 3m used for finding addition is also designated 11'i
It may be changed depending on the position of each pixel within the layer 3x. In order to specify the oblique tomographic plane [3x as described above, it is convenient to use, for example, a joystick as an input means for the tomographic plane 3x.

(Effect of the invention) As explained in detail above, according to the present invention, it is possible to actually
) It is possible to show a tomogram of any tomographic plane other than the ejected area, so just one multi-layer eruption is enough! = Even if there are few decoy images, it is possible to obtain information about all the tomographic planes of the subject.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the state of radiation simultaneous detection and decoding in the image recording section of an apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing an image reading section of an apparatus according to an embodiment of the present invention. , FIG. 3 is a block diagram showing a part of an apparatus according to an embodiment of the present invention, which performs arbitrary tomographic image formation, and FIG. Elevation views, Figures 5.6 and 7 serve as illustrations for explaining the method of the invention. 1... Image recording section 2... Image reading section 10.
...Radiation source 11...Cassette 12...
Subject (subject) 13...Gen Q4 gland 21...Sea 1
~Transporting means 22... Laser light source 23... Laser beam? 4... Optical deflector 25... Stimulated luminescent light 27... Photo multiplier 30... Weighting and pressing section 31... Section 1 plane designating section 3'3... Display, 35 ...Input knob △1
~AIO... Accumulative phosphor sheet 81~ [310...
・Fault plane [3x...Specified fault plane F1 to F10...
・Image files 81 to 310...read image signal 3a..., s1] signal 3s...rejection side designation signal 1st 1 Fig. 3 2 Fig. 1] Fig. 4 Fig. 5 6 is 8m in Figure 7.

Claims (2)

[Claims] (1) A laminate consisting of multiple stimulable phosphor sheets,
Radiation transmitted through the object is irradiated to accumulate and record different tomographic images of the object on these stimulable phosphor sheets, and then excitation light is irradiated to each of the stimulable phosphor sheets to make them shine. The stimulated luminescent light is emitted, and these stimulated luminescent lights are detected photoelectrically to obtain a plurality of sets of image signals each representing the tomographic image, and at least two sets of these image signals are coupled to each other. 1. A method for forming an arbitrary tomographic image, comprising weighting and adding signals for corresponding pixels, inputting the added signal obtained by this addition to an image reproducing device, and forming a tomographic image based on the added signal. (2) In a laminate consisting of multiple stimulable phosphor sheets,
an image recording unit that irradiates radiation that has passed through the subject and accumulates and records different tomographic images of the subject on these stimulable phosphor sheets; each of the stimulable phosphor sheets on which the tomographic images are recorded; an image reading unit that irradiates excitation light to emit stimulated luminescence light and photoelectrically detects the stimulated luminescence light to obtain a plurality of sets of image signals each representing the tomographic image; determining a weighting coefficient for each tomographic image based on storage means for storing signals, tomographic plane specifying means for specifying an arbitrary tomographic plane, and positional information of the tomographic plane specified by this tomographic plane specifying means; An arbitrary tomographic image forming apparatus comprising a weighted addition section that weights and adds at least two sets of image signals read out from the means between corresponding pixels according to the weighting coefficient.