同: electron beam computed tomography

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/06/13 11:14:03」(JST)

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Not to be confused with Electron tomography.

Electron beam tomography (EBT) is a specific form of computed tomography (CAT or CT) in which the X-ray tube is not mechanically spun in order to rotate the source of X-ray photons. This different design was explicitly developed to better image heart structures which never stop moving, performing a complete cycle of movement with each heart beat.

As in conventional CT technology, the X-ray source-point moves along a circle in space around an object to be imaged. In EBT, however, the X-ray tube itself is large and stationary, and partially surrounds the imaging circle. Rather than moving the tube itself, electron-beam focal point (and hence the X-ray source point) is swept electronically along a tungsten anode in the tube, tracing a large circular arc on its inner surface. This motion can be very fast.

Design advantage [edit]

The principal application advantage of EBT tomographic CT machines, and the reason for the invention, is that because the X-ray source-point is swept electronically, not mechanically, it can be swept with far greater speed.

The major medical application for which this design technology was invented in the 1980s was for imaging the human heart. The heart never stops moving, and some important structures, such as arteries, move several times their diameter during each heartbeat. Rapid imaging is, thus, important to prevent blurring of moving structures during the scan. The most advanced current commercial designs can perform image sweeps in as little as 0.025 seconds. By comparison, the fastest mechanically swept X-ray tube designs require about 0.33 seconds to perform an image sweep. For reference, current coronary artery angiography imaging is usually performed at 30 frames/second or 0.033 seconds/frame; EBT is far closer to this than mechanically swept CT machines.

Design specifics [edit]

As in standard X-ray tubes, part of the electron current energy when hitting the tungsten target is converted into photons. However, instead of spinning a small target anode in order to dissipate waste heat, the electron current focus spot is swept along a large stationary target anode.

The electron current sweep is aimed using wound copper coil magnetic deflection yokes, as in a cathode ray tube (CRT). However, the entire structure of the cathode, deflection yokes, anode and overall vacuum tube size is much larger, therefore made out of steel, not glass, with the main central open midsection of the vacuum tube hollow, leaving room for the scan table and object or person to lie while the scan is performed.

Design disadvantage [edit]

Given the vastly larger size and low production volume of the EBT design, only about 120 exist in the world, as of 2004, vs. thousands of more conventional design CT machines.

This CT scanner design has remained more expensive, by over double, than the more widely sold CT design in which a small, more conventional X-ray tube is mechanically spun.

Future [edit]

Whether the inherent sweep-speed advantage will maintain commercial viability of the EBT design remains unclear at this time. As of 2002, one major company owns and offers models in both competing designs, with engineering cross-pollination of techniques between the product design teams. As of 2005, it increasingly appears that the spiral CT designs, especially those with (b) 64 detector rows, (b) 3×360°/sec rotation speeds and designed for cardiac imaging, are largely replacing the EBT design from a commercial and medical perspective. However, EBT still offers sweep speeds of effectively 50×360°/sec rotation speeds and lower radiation exposure. The latest version of the EBT eSpeed offers a 33 ms sweep time.

While there are very few of these scanners in use, this technology represents the fastest commercial CT temporal resolution.

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English Journal

Mitigating arsenic crisis in the developing world: Role of robust, reusable and selective hybrid anion exchanger (HAIX).

German M, Seingheng H, Sengupta AK.Author information Department of Civil and Environmental Engineering, Lehigh University, 1 W. Packer Ave, Bethlehem, PA 18015, United States.AbstractIn trying to address the public health crisis from the lack of potable water, millions of tube wells have been installed across the world. From these tube wells, natural groundwater contamination from arsenic regularly puts at risk the health of over 100million people in South and Southeast Asia. Although there have been many research projects, awards and publications, appropriate treatment technology has not been matched to ground level realities and water solutions have not scaled to reach millions of people. For thousands of people from Nepal to India to Cambodia, hybrid anion exchange (HAIX) resins have provided arsenic-safe water for up to nine years. Synthesis of HAIX resins has been commercialized and they are now available globally. Robust, reusable and arsenic-selective, HAIX has been in operation in rural communities over numerous cycles of exhaustion-regeneration. All necessary testing and system maintenance is organized by community-level water staff. Removed arsenic is safely stored in a scientifically and environmentally appropriate manner to prevent future hazards to animals or people. Recent installations have shown the profitability of HAIX-based arsenic treatment, with capital payback periods of only two years in ideal locations. With an appropriate implementation model, HAIX-based treatment can rapidly scale and provide arsenic-safe water to at-risk populations.
The Science of the total environment.Sci Total Environ.2013 Dec 6. pii: S0048-9697(13)01236-9. doi: 10.1016/j.scitotenv.2013.10.092. [Epub ahead of print]
In trying to address the public health crisis from the lack of potable water, millions of tube wells have been installed across the world. From these tube wells, natural groundwater contamination from arsenic regularly puts at risk the health of over 100million people in South and Southeast Asia. Al
PMID 24321388

Exceptional arsenic (III,V) removal performance of highly porous, nanostructured ZrO2 spheres for fixed bed reactors and the full-scale system modeling.

Cui H, Su Y, Li Q, Gao S, Shang JK.Author information Environment Functional Materials Division, Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Liaoning Province, Shenyang 110016, PR China.AbstractHighly porous, nanostructured zirconium oxide spheres were fabricated from ZrO2 nanoparticles with the assistance of agar powder to form spheres with size at millimeter level followed with a heat treatment at 450 °C to remove agar network, which provided a simple, low-cost, and safe process for the synthesis of ZrO2 spheres. These ZrO2 spheres had a dual-pore structure, in which interconnected macropores were beneficial for liquid transport and the mesopores could largely increase their surface area (about 98 m(2)/g) for effective contact with arsenic species in water. These ZrO2 spheres demonstrated an even better arsenic removal performance on both As(III) and As(V) than ZrO2 nanoparticles, and could be readily applied to commonly used fixed-bed adsorption reactors in the industry. A short bed adsorbent test was conducted to validate the calculated external mass transport coefficient and the pore diffusion coefficient. The performance of full-scale fixed bed systems with these ZrO2 spheres as the adsorber was estimated by the validated pore surface diffusion modeling. With the empty bed contact time (EBCT) at 10 min and the initial arsenic concentration at 30 ppb, the number of bed volumes that could be treated by these dry ZrO2 spheres reached ~255,000 BVs and ~271,000 BVs for As(III) and As(V), respectively, until the maximum contaminant level of 10 ppb was reached. These ZrO2 spheres are non-toxic, highly stable, and resistant to acid and alkali, have a high arsenic adsorption capacity, and could be easily adapted for various arsenic removal apparatus. Thus, these ZrO2 spheres may have a promising potential for their application in water treatment practice.
Water research.Water Res.2013 Oct 15;47(16):6258-68. doi: 10.1016/j.watres.2013.07.040. Epub 2013 Aug 13.
Highly porous, nanostructured zirconium oxide spheres were fabricated from ZrO2 nanoparticles with the assistance of agar powder to form spheres with size at millimeter level followed with a heat treatment at 450 °C to remove agar network, which provided a simple, low-cost, and safe process for the
PMID 23978657

Pretreatment of 2,4-dinitroanisole (DNAN) producing wastewater using a combined zero-valent iron (ZVI) reduction and Fenton oxidation process.

Shen J, Ou C, Zhou Z, Chen J, Fang K, Sun X, Li J, Zhou L, Wang L.Author information Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu Province, China. shenjinyou-1981@163.comAbstractA combined zero-valent iron (ZVI) reduction and Fenton oxidation process was tested for the pretreatment of 2,4-dinitroanisole (DNAN) producing wastewater. Operating conditions were optimized and overall performance of the combined process was evaluated. For ZVI process, almost complete reduction of nitroaromatic compounds was observed at empty bed contact time (EBCT) of 8h. For Fenton process, the optimal pH, H₂O₂ to Fe(II) molar ratio, H₂O₂ dosage and hydraulic retention time (HRT) were found to be 3.0, 15, 0.216 mol/L and 5h, respectively. After pretreatment by the combined ZVI-Fenton process under the optimal conditions, aromatic organic compound removal was as high as 77.2%, while the majority of COD remained to be further treated by sequent biological process. The combined anaerobic-aerobic process consisted of an anaerobic baffled reactor (ABR) and a moving-bed biofilm reactor (MBBR) was operated for 3 months, fed with ZVI-Fenton effluent. The results revealed that the coupled ZVI-Fenton-ABR-MBBR system was significantly efficient in terms of correcting the effluent's main parameters of relevance, mainly aromatic compounds concentration, COD concentration, color and acute toxicity. These results indicate that the combined ZVI-Fenton process offers bright prospects for the pretreatment of wastewater containing nitroaromatic compounds.
Journal of hazardous materials.J Hazard Mater.2013 Sep 15;260:993-1000. doi: 10.1016/j.jhazmat.2013.07.003. Epub 2013 Jul 10.
A combined zero-valent iron (ZVI) reduction and Fenton oxidation process was tested for the pretreatment of 2,4-dinitroanisole (DNAN) producing wastewater. Operating conditions were optimized and overall performance of the combined process was evaluated. For ZVI process, almost complete reduction of
PMID 23892166

Japanese Journal

Coronary Artery Calcification by Computed Tomography in Epidemiologic Research and Cardiovascular Disease Prevention

Journal of epidemiology 22(3), 188-198, 2012-05-01
NAID 10030617938

Small Coronary Calcium Deposits and Elevated Plasma Levels of Oxidized Low Density Lipoprotein are Characteristic of Acute Myocardial Infarction

Journal of atherosclerosis and thrombosis 15(2), 75-81, 2008-04-30
NAID 10022608007

壮年期男性における飲酒と潜在性動脈硬化の関連についての疫学研究 : 電子ビームCTによる冠動脈石灰化を指標として

日本アルコール・薬物医学会雑誌 = Japanese journal of alcohol studies & drug dependence 41(3), 184-185, 2006-06-28
NAID 10018014332

Related Pictures

EBCT Scanner An EBCT scan shows calcification in the EBCT images of two human hearts: a normal CT Scan Tips & Protocols: Electron beam CT 正常心脏大血管EBCT增强扫描 Why HeartScan & EBCT 2nd Generation EBCT Concept Using Empty-Bed Contact Time (EBCT) To

★リンクテーブル★

リンク元	「超高速CT」
関連記事	「EB」

「超高速CT」

Electron beam tomography
	Intervention
	; Patent illustration showing a cutaway view of an electron beam computerized tomography system. Components are 22. electron gun, 23. electron beam, 24. focus coil, 27. beam bending coil, 28-31. target rings, 14. detector array, 11. scan tube. The electron beam creates x-rays at the target rings, which radiates through the patient to the detector on the opposite end of the scan tube.
MeSH	D014057
OPS-301 code:	3-26

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英: ultra-fast CT, ultrafast CT, UFCT, dynamic spatial reconstructor, DSR
同: 電子ビーム走査型CT, electron-beam CT, EBCT

「EB」

　　[★]

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案内

EBCT