WO2007142385A1

WO2007142385A1 - A x-ray computer tomography

Info

Publication number: WO2007142385A1
Application number: PCT/KR2006/003454
Authority: WO
Inventors: Kwon-Ha Yoon; Kyugyeom Kim; Jaehee Kim; Kyongwoo Kim; Jonghwan Min
Original assignee: Wonkwang University Center For Industry-Academy Cooperation
Priority date: 2006-06-08
Filing date: 2006-08-31
Publication date: 2007-12-13
Also published as: KR20070117392A; KR100880864B1

Abstract

A nano-scale X-ray computer tomography (CT) scanner includes an X-ray generator for generating the X-ray emitted to the biopsy sample, a holder that is provided at a side of the X-ray generator to fix the biopsy sample, an X-ray detector that is provided at a side of the holder to convert photons of the X-ray generated from the X-ray generator and passing through the biopsy sample into electrons and take an image through multiplication of the electrons, a cooling unit that is provided at a side of the holder to cool the biopsy sample so that the biopsy sample fixed on the holder is not dead, a driving unit that is provided at lower ends of the holder and the X-ray detector to align the X-ray generator, the holder, and the X-ray detector on an optical axis, and a controller for controlling the X-ray generator, the holder, the X-ray detector, the cooling unit, and the driving unit, restructuring the image taken by the X-ray detector into the three-dimensional image, and outputting the three-dimensional image.

Description

A X-RAY COMPUTER TOMOGRAPHY

Technical Field The present invention relates to an X-RAY computer tomography (CT) scanner and, more particularly, to a nano- scale X-ray computer tomography canner that enables an observation of a nano-scaled structural variation without destroying the cellular cell by doing a CT scan for a biopsy sample at a nano-scale resolution.

Background Art

Generally, a computer tomography (CT) is a technology, which was invented by Godfrey Newbold Hounsfield and on the market in 1971, for displaying an image on information of a structure or tissue of an object that could not be obtained by a conventional X-ray device. That is, the CT is a technology for displaying a three-dimensional image of the object from a series of two-dimensional images taken around a single axis of rotation. By using the three-dimensional image, an image of each section of the object can be identified and a variety of internal structures of the object can be dissembled and displayed.

A CT scanner includes an X-ray generator, a mechanical unit for rotating an object to be tested, and a detector. The object to be test is located on a linear line connecting the X-ray generator to the detector to emit the X-rays in a cross-sectional direction of the object from a variety of directions. At this point, when the detector collects data on an absorption difference due to an attenuation coefficient between materials by the emitted X-rays and the data is converted into sectional images. Next, the digital sectional image data generated from different directions is calculated through an arithmetic operation using a computer to restructure and display the CT image. In addition, the X-ray CT scanners may be classified into medical canners and industrial scanners in accordance with kinds of objects to be taken, an observing area, and a purpose of doing a CT scan for the object and thus have been widely used.

Particularly, as a biotechnology and related industries have been developed, the X-ray CT scanners for a biomedical have been widely used. In the biotechnology field, a technology for taking a picture of a biopsy sample such as an experimental rat at a high resolution has been spotlighted.

However, since the CT scanner that is currently developed has a micro-scale resolution, it has a drawback in that it cannot be widely used for a variety of researches such as a gene expression study, a protein study, a toxic test, a development of a new drug, a cell differentiation study, a structural abnormality study, a soil/plant study, a natural fiber and protein study, and a study of an artificial mixed material using a function research. Further, the current CT scanner is designed to fix the biopsy sample to be tested using a holder. That, is, the biopsy sample is tested through a series of processes such as a tissue removal process from an animal and a fixing process on the holder. During these processes, the removed tissue is converted into a dead tissue as predetermined time passes. Therefore, the scanning of the biopsy sample should be quickly done. This makes it difficult to take a precise tissue image.

Furthermore, as the CT scanner performs the CT scan using X-rays, the tissue of the biopsy sample may be deformed of polluted by radiation of the X-rays. This also makes it difficult to take a precise tissue image.

Disclosure Technical Problem The present invention has been made in an effort to solve the above-described problems. It is an object of the present invention to provide a nano-scale X-ray CT scanner that can take an image having a nano-scale image using an X- ray generator having a focal spot equal to or less than lum.

It is another object of the present invention to provide a nano-scale X-ray CT scanner that can increase allowable test time of a biopsy sample by providing a cooling unit to a holder fixing the sample and thus by freshly maintaining and protecting the sample fixed on the holder from X-ray radiation.

Technical Solution

To achieve the objects, the present invention provides a nano-scale X-ray computer tomography (CT) scanner that executes a CT scan for a biopsy sample using an X-ray and restructures a CT image into a three-dimensional image, including: an X-ray generator for generating the X-ray emitted to the biopsy sample; a holder that is provided at a side of the X-ray generator to fix the biopsy sample; an X- ray detector that is provided at a side of the holder to convert photons of the X-ray generated from the X-ray generator and passing through the biopsy sample into electrons and take an image through multiplication of the electrons; a cooling unit that is provided at a side of the holder to cool the biopsy sample so that the biopsy sample fixed on the holder is not dead; a driving unit that is provided at lower ends of the holder and the X-ray detector to align the X-ray generator, the holder, and the X-ray detector on an optical axis,- and a controller for controlling the X-ray generator, the holder, the X-ray detector, the cooling unit, and the driving unit, restructuring the image taken by the X-ray detector into the three-dimensional image, and outputting the three- dimensional image. The X-ray generator may have a focal spot having a sub- nano-scale equal to or less than lum and may be formed in a transmission type.

The cooling unit may includes a gas storing tank for storing cooling gas; a gas supplying pipe that is connected between the gas storing tank and the holder to supply the cooling gas to the gas supplying pipe; and a discharge pump located at a side of the gas supplying pipe to discharge the gas stored in the gas supplying pipe to an external side. The nano-scale X-ray CT scanner may further include a sub- tank that is provided at a side of the gas supplying pipe and stores cooling liquid for cooling the gas flowing along the gas supplying pipe .

The driving unit may include a table; a holder moving station that is provided at a side of the table to move the holder along X, Y, and Z-axes; a rotating station for rotating the holder; a detector moving station that is provided at another side of the table to move the X-ray detector along the X, Y, and Z-axes; and a controller that drives the table and the stations by generating an alignment control to align rotational positions and the X, Y, and Z- axes of the table and the stations. The driving unit may be an air-bearing type using pneumatic, which can minimize a position aliment error that may be incurred in a contact - driving type and realize a highly precise position alignment.

The nano-scale X-ray CT scanner may further include a heat dissipation unit provided between the holder and the driving unit to prevent very low temperature heat from being transferred to the driving unit when the biopsy sample maintains the very low temperature state by the cooling unit provided at the side of the holder.

Advantageous Effects

According to the present invention, an image having a nano-scale resolution can be taken using the X-ray generator having a focal spot equal to or less than lum. Further, by providing the cooling unit to the holder fixing the sample, the sample can be freshly maintained and protected from the X-ray radiation and thus allowable time for testing the sample can be significantly increased.

Description of Drawings

FIG. 1 is a schematic diagram of a nano-scale X-ray CT scanner according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating an X-ray generator, a holder, an X-ray detector, and a driving unit according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of a cooling unit according to an embodiment of the present invention.

FIG. 4 is a photograph of a biopsy same taken by the nano-scale X-ray CT scanner of the present invention.

Best Mode for Carrying out the Invention

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

FIG. 1 is a schematic diagram of a nano-scale X-ray CT scanner according to an embodiment of the present invention, FIG. 2 is a perspective view illustrating an X-ray generator, a holder, an X-ray detector, and a driving unit according to an embodiment of the present invention, FIG. 3 is a schematic diagram of a cooling unit according to an embodiment of the present invention, and FIG. 4 is a photograph of a biopsy same taken by the nano-scale X-ray CT scanner of the present invention. Referring to the drawings, a nano-scale X-ray CT scanner includes an X-ray generator 10, a holder 20, which is located at a side of the X-ray generator 10 and on which a biopsy sample that will be tested is disposed and fixed, an X-ray detector 30 located at a side of the holder 20, a cooling unit 40 located at a side of the holder 20, a driving unit 50 provided on a lower end of the holder 20 and the X-ray generator 30, and a controller 60 for controlling the units.

The units may be installed in a room 1. The room 1 is provided to prevent researchers from being exposed to radiation of X-rays emitted from the X-ray generator 10.

The room 1 is formed of lead and provided with a door through which the researcher can go in and out .

The X-ray generator 10 has a focal spot equal to less than lum. The X-ray generator 10 may be formed in a transmission type having nanotubes.

Generally, the X-ray generator 10 generates X-rays as electrons emitted from a cathode collide with an anode target surface. A distance from an actual light generation point to an output end may be varied in accordance with a structure of the X-ray generator 10. The X-ray generator 10 may be classified in accordance with its structure into a reflective type and a transmission type. The reflective type X-ray generator has a drawback in that a geometrical magnification cannot be further increased since the actual light generation point is far from the output end. Therefore, it is preferable to use the transmission type X- ray generator.

In the transmission type X-ray generator haiving the nanotubes, since the light generation point is very close to the output end, the biopsy sample can be located near the light generation point as close as possible. In addition, since the transmission type X-ray generator has the focal spot equal to or less than lum, the blurring phenomenon of the image can be reduced. When the transmission type X-ray generator uses a phase-difference phenomenon, a clear image having a high resolution can be obtained.

The holder 20 is provided to fix the biopsy sample. The holder 20 may be formed of a material that does not interfere with the X-rays when the X-rays are transmitted through the sample. The holder 20 may be formed in a capillary shape. Further, the holder 20 may be detachably assembly so as to make it easy to fix the biopsy sample.

A heat dissipation unit 70 is provided on a lower end of the holder 20. The heat dissipation unit 70 prevents heat from being transferred to the driving unit provided on the lower end of the holder 20 as a very low temperature state is maintained by the cooling unit 40.

When the X-rays generated by the X-ray generator 10 are incident on the biopsy sample fixed on the holder 20, the X- ray detector 30 converts photons into electrons on a photoemission surface and obtains a CT image through the multiplication of the electrons.

Describing the X-ray detector 30 in more detail, the X- ray detector 30 multiplicates the electrons converted on the photoemission surface using a micro channel plate (MCP) , and excites phosphors by allowing the multiplicated electrons to collide with ■ the phosphors, and imaging the multiplicated light a charge-coupled device (CCD) camera using a relay optics or a fiber optic plate (FOP) , thereby obtaining an image.

Meanwhile, one electron incident on the MCP generates a plurality of secondary electrons when it collides with the phosphor. The generated secondary electrons are accelerated by a voltage applied and generate another secondary electrons. The multiplication factor is about 100 times when a piece of the MCP is used. That is, one electron can generate about 1000 secondary electrons. Therefore, a high sensitivity multiplication camera can be realized.

The cooling unit 40 includes a gas storing tank 42 for storing cooling gas, a gas supplying pipe 44 that is connected between the gas storing tank 42 and the holder 20 to supply the cooling gas to the gas supplying pipe 44, and a discharge pump 46 located at a side of the gas supplying pipe 44. The cooling unit 40 functions to prevent the biopsy sample from being dead. A sub-tank 48 may be further provided at a side of the gas supplying pipe 44 to cool the cooling gas flowing along the gas supplying pipe 44.

Further, the cooling gas may be helium gas. The sub- tank 48 may be filled with liquefied nitrogen. At this point, the helium gas maintains a very low temperature state equal to or less than IOOK (K is a unit of absolute temperature) to cool the biopsy sample at the very low temperature . In order to prevent moisture contained in air around the holder 20 from being frozen by the cooling gas flowing along the gas supplying pipe 44, the discharge pump 46 discharges the cooling gas flowing along the gas supplying pipe 44. By doing this, the freezing of the moisture can be prevented and the biopsy sample can be maintained at the very low temperature .

Particularly, as the cooling unit 40 cools the biopsy sample fixed on the holder 20 at the very low temperature, the life of the biopsy sample can be maintained and the modification or destroy of the cell of the biopsy sample, which is caused by the radiation of the X-rays, can be prevented. As a result, a cell image having a high resolution can be obtained.

The driving unit 50 includes a table 52, a holder moving station 54 that is provided at a side of the table to move the holder along X, Y, and Z-axes, a rotating station 56 for rotating the holder 20, a detector moving station 58 that is provided at another side of the table to move the X- ray detector 30 along the X, Y, and Z axes, and a controller for controlling the stations.

The driving unit 50 is an air-bearing type driving unit using pneumatic, which can, as the stations are driven in a state where they are spaced apart from each other by the pneumatic, minimize a contacting error, sliding error, backlash, and a shape error such as twisting error or planarizing error and thus can realize a precise alignment and control .

Further, in order to provide the pneumatic to each station of the driving unit 50, an air compressor C generating air pressure is provided and a drier D is provided at a side of the air compressor C to remove the moisture contained in the compressor air. This is well known in the art .

The controller 60 is installed out of the room 1. The controller 60 remote-controls the X-ray generator 10, holder 20, X-ray detector 30, cooling unit 40, and driving unit 50 that are installed in the room 1. In addition, the controller 60 restructures the CT image taken by the X-ray detector 30 into a three-dimensional image and outputs the three-dimensional image.

In use of the above-described nano-scale X-ray CT scanner, a first alignment process for aligning the X-ray generator 10, the holder 20, and the X-ray detector 30 on an optical axis is first performed. At this point, since the X-ray generator 10 is fixed on the room 1, the first alignment process is performed while moving the holder 20 and the X-ray detector 30 using the holder moving station 54 and the detector moving station 58 of the driving unit 50.

When the first alignment process is finished, the biopsy sample is fixed on the holder 20. At this point, a final location alignment on the optical axis is finished through the first alignment process.

Because the operation is remotely controlled by the controller 60, it is possible to prevent safety accident that causes operators to be exposed to radioactivity.

Further, in order to prevent the biopsy sample fixed on the holder 20 from being dead, cooling gas is supplied to the holder 20 along the gas supplying pipe 44 from the gas supplying tank 42 of the cooling unit 40. At this point, the cooling gas is supplied at the very low temperature equal to or less than IOOK by the sub-tank 48 provided at a side of the gas supplying pipe 44. In addition, the cooling gas is discharged by the discharge pump 46 provided at a side of the gas supplying pipe 44, the freezing of the moisture contained in the air around the holder 20 is prevented and thus the transmittance of the X-rays can be improved.

When the biopsy sample is prepared, the X-ray generator 10 emits an X-ray having a focal spot equal to or less than lum and is incident on the X-ray detector 30 after passing through the biopsy sample. As a result, the X-ray detector 30 can obtain the CT image.

Particularly, since the holder 20 is designed to step- rotate by a predetermined angle by the rotating station 56, the CT image of the biopsy sample at each rotating angle can be captured by the X-ray detector. The CT images are transferred to the controller 60 and restructured as the three-dimensional image.

Meanwhile, as the biopsy sample that is fixed on the holder 20 for a predetermined testing time is maintained at the very low temperature, the pollution by the radiation can be prevented and the living state can maintained, the image having the high resolution can be obtained.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. A nano-scale X-ray computer tomography (CT) scanner that executes a CT scan for a biopsy sample using an X-ray and restructures a CT image into a three-dimensional image, comprising: an X-ray generator (10) for generating the X-ray emitted to the biopsy sample; a holder (20) that is provided at a side of the X-ray generator (10) to fix the biopsy sample; an X-ray detector (30) that is provided at a side of the holder (20) to convert photons of the X-ray generated from the X-ray generator (30) and passing through the biopsy sample into electrons and take an image through multiplication of the electrons; a cooling unit (40) that is provided at a side of the holder (20) to cool the biopsy sample so that the biopsy sample fixed on the holder (20) is not dead; a driving unit (50) that is provided at lower ends of the holder (20) and the X-ray detector (30) to align the X- ray generator (10) , the holder (20) , and the X-ray detector (30) on an optical axis; and a controller (60) for controlling the X-ray generator (10) , the holder (20) , the X-ray detector (30) , the cooling unit (40) , and the driving unit (50) , restructuring the image taken by the X-ray detector (30) into the three- dimensional image, and outputting the three-dimensional image .

2. The nano-scale X-ray CT scanner of claim 1, wherein the X-ray generator (10) has a focal spot having a sub-nano-scale equal to or less than lum and is formed in a transmission type.

3. The nano-scale X-ray CT scanner of claim 1, wherein the cooling unit (40) comprises: a gas storing tank (42) for storing cooling gas; a gas supplying pipe (44) that is connected between the gas storing tank (42) and the holder (20) to supply the cooling gas to the gas supplying pipe (44) ; and a discharge pump (46) located at a side of the gas supplying pipe (44) to discharge the gas stored in the gas supplying pipe (44) to an external side.

4. The nano-scale X-ray CT scanner of claim 3, further comprising a sub-tank (48) that is provided at a side of the gas supplying pipe (44) and stores cooling liquid for cooling the gas flowing along the gas supplying pipe (44) .

5. The nano-scale X-ray CT scanner of claim 1, wherein the driving unit (50) includes a table (52); a holder moving station (54) that is provided at a side of the table to move the holder along X, Y, and Z-axes ; a rotating station (56) for rotating the holder (20) ; a detector moving station (58) that is provided at another side of the table to move the X-ray detector (30) along the X, Y, and Z axes; and a controller that drives the table (52) and the stations by generating an alignment control to align rotational positions and the X, Y, and Z-axes of the table (52) and the stations.

6. The nano-scale X-ray CT scanner of claim 1 or 5 , wherein the driving unit (50) is an air-bearing type using pneumatic, which can minimize a position aliment error that may be incurred in a contact-driving type and realize a highly precise position alignment.

7. The nano-scale X-ray CT scanner of claim 1, further comprising a heat dissipation unit (70) provided between the holder (20) and the driving unit (50) to prevent very low temperature heat from being transferred to the driving unit (50) when the biopsy sample maintains the very low temperature state by the cooling unit (40) provided at the side of the holder (20) .