JPS59177026A - X-ray tomographic image enlarging apparatus - 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 (Description of Technical Field) The present invention relates to an X-ray tomographic image enlarging apparatus that enlarges and reproduces an X-ray tomographic image.

In particular, this device can be used to non-invasively observe the fine structure of human tissue, so it is expected to have wide applications in the medical field. Objects that are the subject of zoology and botany can be observed in the same way.

(Description of Prior Art) An X-ray CT apparatus is known as a system that can non-invasively observe tomographic images of a living body.

The limit of the magnification effect by the X-ray flux in this device is approximately twice that.

Furthermore, considering the diameter of the focus of the currently used X-ray source and the size of the detector, the limiting resolution cannot exceed 100 μm.

When it is necessary to observe with greater magnification,
Observation must be performed using a well-known optical microscope.

However, observation using the optical microscope requires cutting out a specimen from living tissue, which destroys the tissue.

Therefore, there is a strong demand for non-(A) magnified observation while maintaining a certain resolution.

(Detailed Description of the Invention) The purpose of the present invention is to elucidate the cause of limitations on image magnification in the X-ray CT apparatus, and to solve the problem to achieve a certain resolution without destroying tissue. An object of the present invention is to provide an X-ray tomographic image magnifying device that can maintain and magnify observation.

(Detailed Description of the Invention) In order to achieve the above object, an X-ray tomographic image enlarging device according to the present invention includes an X-ray generating device having a focal point with an extremely small diameter;
a sample stage supporting a sample that is irradiated with X-rays emitted by the radiation generator; and a sample stage located at a position away from the sample to image the X-ray intensity distribution that is spatially modulated and expanded by passing through the sample. an X-ray image pickup device disposed in line with the sample supported on the sample stage;
a rotation mechanism that performs relative rotation between a sample stage and an axis connecting an X-ray incident surface of the X-ray image capturing device and the X-ray generating device in order to be rotationally scanned by the X-rays emitted by the ray generating device; It is comprised of a calculation unit that calculates the output for each predetermined rotational position of the imaging device to reconstruct an enlarged tomographic image, and an output device that outputs the calculation data of the calculation unit.

The X-ray generating device has a focal point with an extremely small diameter, and the X-ray image intensifying device has high resolution.
The ray generating device allows for large magnification at the X-ray flux stage due to the extremely small diameter deep point and the arrangement of the sample and the X-ray image intensifier.

(Description of Examples) Hereinafter, the present invention will be described in more detail with reference to the drawings and the like.

FIG. 1 is a block diagram showing an embodiment of an X-ray tomographic image enlarging apparatus according to the present invention. This embodiment device comprises an X-ray image intensifying device 4, an enlarging optical system 5 for enlarging and projecting the fluorescent light It, 4f formed on the fluorescent surface 4e of the X-ray image intensifying device 4. and an imaging device 6 for capturing a fluorescent image 6a magnified by the magnifying optical system 5.

FIG. 2 is a schematic diagram for explaining the rotating direction of the sample stage of the apparatus and the scanning direction of the TI image device.

The present invention uses an X-ray generator 1 that is operated at a relatively low voltage and has a focal point diameter of about 1 to 10 μm.

Here, the modulation of X-ray intensity by the sample will be explained.

In order to reconstruct a tomographic image of a sample using an X-ray projection image, the intensity of the X-rays transmitted through the sample must be modulated by the sample.

If the sample is made of a metal with a large attenuation coefficient or has a considerable thickness, it may be necessary to use strong X-rays, and even if strong X-rays are used, sufficient modulation can be obtained.

Iron plate (Fc) is 1.97 x for 20KeV X-rays
It has a linear attenuation coefficient of 10 Qficm.

Q, when a 1 mm thick iron plate is irradiated with 20 Ke VOX rays, the ratio of the intensity of the irradiated X-rays to Iin and the intensity of transmitted X-rays 1out is given by the following equation.

I out / I 1n=exp (1
,97* 100 *0.013-〇, 14 Water (H2O) has a linear attenuation coefficient of 0.775/cm for 20 KeV X-rays.

The linear attenuation coefficient of the microstructure of the soft tissue of living organisms is determined by the aforementioned water (H
20), it is understood that 20 KeV X-rays are too strong when observing the soft tissues of living organisms.

Therefore, in the apparatus according to the present invention, relatively weak X-rays of about 5 K e V are used.

The linear attenuation coefficient of the fine structure of the soft tissue of living organisms is 5Ke■
It is about 42 cm to the line.

Using this number, the above 1 out / I in for the fine structure of the soft tissue of a biological body with a thickness of 0.1 mm is calculated as follows.

I out / I in = exp (-42*'
0.01)=0.66 The X-ray generator 1 emits a fan-shaped X-ray flux as shown in FIG.

A sample 2 is placed on the sample stage 3 so as to be irradiated with fan-shaped X-rays emitted by the X-ray generator 1.

The surface within the sample 2 that is transmitted by the fan-shaped X-rays is the object of magnification.

In order to enlarge and detect the spatially modulated X-ray intensity distribution by passing through the sample 2, an
A line image intensifier 4 is arranged.

If the distance from the focal point of the X-ray generator 1 to the sample 2 is b, and the distance from the focal point of the X-ray generator 1 to the X-ray image intensifier 4 is a, then a/b expansion at the X-ray stage will be held.

Here, the size of the focal point of the X-ray generator 1 and the modulation transfer function M
The relationship between TFs will be explained with reference to FIGS. 3 and 4.

The spatial frequency on the surface of sample (object) 2 is U. The spatial frequencies at the focal plane and detection plane (input plane of the X-ray image intensifier 4 in the embodiment shown in FIG. 1) of the X-ray generator 1 corresponding to , , and the like are respectively uF and uS.

Also x. =1/u.

x F = 1 / u’F x-s = l / u s shall be.

X[++ xF, xs are each 110. LIF,'
This is the period corresponding to 133.

Since the magnification ratio M is a/b as described above, the following relationship holds true.

x6 = (b/a)*xs xF=(b/(a-b))*xS xF=(a/(a-b'))*x.

=　CM/　(M-1〉)　HiX.

, ゛, u F −((M 1 ) /M)' *
uo ・-1t1 Also, the focus is half value 'I@2 H's Q
When the intensity distribution is of the au, ss distribution type, the modulation transfer function M-D with respect to the spatial frequency uF on the focal plane is MTF = exp (-44, 23* (H* u
F) 2) −(21).

The relationship between equations (1) and (2) is shown graphically in FIG.

When we examine Figure 4 using specific numerical values, we find that the spatial frequency on the surface of sample (object) 2 is uo = 1007!
p / m'm If the magnification rate M is M-10 and the focal point has a half-width of 2H and 2H = 4 μm, then The spatial frequency is uF #907! p/mm, and it can be seen that a value of about 60% is obtained as the focal MTF.

In the present invention, the focus of the X-ray generator 1 needs to have a relatively small diameter in order to obtain high resolution.

This requirement can be easily met with relatively weak X-ray equipment. Furthermore, as mentioned above, it meets the demand for using a relatively weak X-ray device from the viewpoint of modulation.

A thin helium plate 4a on the surface of the X-ray imaging device 4 forms part of a vacuum vessel, and a pair of a scintillator and a photocathode 4b is provided adjacent to the helium plate 4a.

Photoelectrons from the photocathode 4b are imaged by an electron lens 4c onto the input surface of a microchannel plate 4d and multiplied by the microchannel plate 4d.

This multiplied electron image forms a fluorescent image with a linear intensity distribution corresponding to the spatially modulated X-ray intensity distribution on the fluorescent surface 4e. An example of the intensity distribution of this fluorescent image is shown in 4f.

This embodiment is configured so that the sample 2 is rotationally scanned by the X-rays emitted by the X-ray generator 1 by intermittently rotating the sample stage 3 at a fixed angle (for example, bi).

Since such a rotation mechanism is well known, it is omitted from the drawing.

FIG. 2 shows the rotation direction of the sample stage 3.

The image 4f formed on the fluorescent surface 4e corresponding to the spatially modulated X-ray intensity distribution is magnified by about 10 times by the enlarging optical system 5, and is displayed on the photocathode of the image pickup tube 6 with an intensity distribution as shown in 6a. The image is formed into a line.

The scanning direction of the image pickup tube 6 does not perform vertical scanning along the line of the image. Alternatively, vertical scanning is performed only within the width of the image. This scanning is performed every stationary period in synchronization with the intermittent rotation of the sample stage 3.

The signal from the image pickup tube 6 is converted by an A/D converter 7 and sequentially stored in a sofa memory 8.

The arithmetic unit 9 processes the data accumulated in the buffer memory 8 by /J
ii calculation to reconstruct the tomographic image.

As a method for this reconstruction, a back projection method, which is a CT method, can be used.

First, the convolution of the filter function and the projection take is calculated for each rotation, and the result is projected onto each element of the nxn matrix from the corresponding projection angle. Data for each rotation angle is added to each element of the n×n matrix. Since each element of the nxn matrix corresponds to one pixel, the data is reconstructed so that it can be displayed in different colors or in shading.

The reconstructed pixel take is stored in the memory 11 and used on a display 10 such as a television monitor or other DJs such as a printer.
output by the power device 12.

Various modifications can be made to the embodiments described in detail above within the scope of the present invention.

The apparatus of the embodiment includes the X-ray image pickup device, an X-ray image intensifier 4, and an enlarging optical system 5 for enlarging and projecting a fluorescent image 4f formed on a fluorescent surface 4e of the X-ray image intensifying device 4. , an image pickup tube 6 for picking up a fluorescent image 6a magnified by the magnifying optical system 5. A one-dimensional solid-state image sensor can be used instead of the image pickup tube. However, in this case, in order to ensure sufficient resolution, it is necessary to perform a larger magnification than the magnification of the magnifying optical system 5 in the case of the image pickup tube 6.

In addition, an image pickup tube 6 capable of directly capturing an X-ray image is used, and this is placed at the position of the X-ray image intensifier 4 in FIG. 1, thereby omitting the X-ray image intensifier 4 and the enlarging optical system 5. You can also do that.

(Detailed Description of the Invention) The present invention, etc. uses an X-ray generator 1 of 1 to 10 μm F.
W HM (F W HM - half width - Full width
We have obtained experimental results that closely match the above-mentioned trial calculation results by enlarging tomographic images of living body soft tissues using a device with an ultra-fine focus of 1000 yen (th atbalf Maximum).

The spatial resolution of conventional X-ray CT equipment is at most 1βp/
On the other hand, the apparatus according to the present invention observes a sample containing a microstructure of about 100 μm. Magnified observation with a high resolution of about p/mm has become possible.

That is, according to the device of the present invention, it has become possible to non-invasively magnify and observe the soft tissue of a living body, which was previously considered impossible.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the X-ray tomographic image enlarging apparatus according to the present invention. FIG. 2 is a schematic diagram for explaining the rotating direction of the sample stage and the scanning direction of the imaging device. FIG. 3 is a schematic diagram for explaining the magnification of the X-ray flux stage. FIG. 4 is a graph showing the relationship between spatial frequency, focal spot size, and frequency transfer function. ■...X-ray generator 2...Sample 3...Sample stand 3a...Rotation center axis of sample stand 4...X-ray image intensifier 5...Enlargement optical system 6...Imaging Device 7...Δ/D converter 8...Buffer memory 9...Arithmetic device 10...Display device 11...Memory 12...Output device Patent applicant Hamamatsu Television Co., Ltd. Agent Patent attorney Ino B. Jusai 1st figure, 2nd figure, 3rd figure

Claims (7)

[Claims] (1) An X-ray generator with an extremely small diameter focal point, a sample stage that supports a sample that is irradiated with X-rays emitted by the X-ray generator, and an X-ray that is spatially modulated and expanded by passing through the sample. an X-ray image pickup device disposed at a position away from the sample in line with the sample supported on the sample stage in order to image the X-ray intensity distribution of the sample; a rotation mechanism for relative rotation between the axes connecting the sample stage, the X-ray generating device, and the X-ray incident surface of the X-ray image capturing device, and a predetermined position of the imaging device; An X-ray tomographic image enlarging device comprising: a computation section that computes outputs for each rotational position to reconstruct an enlarged tomographic image; and an output device that outputs data computed by the computing section. (2) The X-ray tomographic image enlarging device according to claim 1, wherein the X-ray generating device is operated at a relatively low voltage, and the diameter of the focal point is about 1 to 10 μrn. (3) The X-ray tomographic image enlarging apparatus according to claim 1, wherein the output device is a television monitor device that reproduces the calculation results. (4) The X-ray tomographic image enlarging apparatus according to claim 1, wherein the output device is an output device that outputs the contents of a storage device that stores calculation results. (5) Claim 1, wherein the X-ray image pickup device is an image pickup device using an image pickup tube having a photocathode sensitive to X-rays]
The X-ray tomographic image magnifying device described in J. (6) The X-ray image capturing device includes an X-ray image intensifier and the
An X-ray tomographic image magnifying device according to claim 1, comprising an imaging device that images a fluorescent image formed on a fluorescent surface of a line image intensifying device. (7) The X-ray image capturing device includes an X-ray image intensifier and the
Claim 1, comprising: an enlarging optical system for enlarging and projecting a fluorescent image formed on a fluorescent surface of a line image intensifier; and an imaging device for capturing an enlarged fluorescent image by said enlarging optical system. The X-ray tomographic image magnifying device according to item 1.