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 is reflected by the target rings through the patient, to the detector on the opposite end of the scan tube.

Electron beam tomography (EBT) is a specific form of computed axial 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 complex complete cycle of movement with each heart beat. Image File history File links US_patent_4672649_Fig_2. ... Image File history File links US_patent_4672649_Fig_2. ... CT apparatus in a hospital Computed axial tomography (CAT), computer-assisted tomography, computed tomography, CT, or body section roentgenography is the process of using digital processing to generate a three-dimensional image of the internals of an object from a large series of two-dimensional X-ray images taken around... An X-Ray tube is a vacuum tube designed to produce man made X-Ray photons on demand. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ...

As in conventional CT technology, the X-ray source still rotates around the circle in space containing an object to be imaged tomographically, but the X-Ray tube is much larger than the imaging circle and the electron beam current within the vacuum tube is swept electronically, in a circular (partial circle actually) path and focused on a stationary tungsten anode target ring. Structure of a vacuum tube diode Structure of a vacuum tube triode In electronics, a vacuum tube, electron tube, or (outside North America) thermionic valve or just valve, is a device used to amplify, switch or modify a signal by controlling the movement of electrons in an evacuated space. ... For other uses, see Tungsten (disambiguation). ...

Design advantage

EBT Machine

The principal application advantage of EBT tomographic CT machines and the reason for the invention, is that the X-Ray source is swept electronically, not mechanically, and can thus be swept with far greater speed than with conventional CT machines based on mechanically spun X-Ray tubes. EBT Machine File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...

The major medical application for which this design technology was invented in the 1980s, namely 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. The heart and lungs, from an older edition of Grays Anatomy. ... The heart and lungs, from an older edition of Grays Anatomy. ... This article is about the unit of time. ... The coronary circulation consists of the blood vessels that supply blood to, and remove blood from, the heart. ... Angiography or arteriography is a medical imaging technique in which an X-ray picture is taken to visualize the inner opening of blood filled structures, including arteries, veins and the heart chambers. ...

Design specifics

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. An X-Ray tube is a vacuum tube designed to produce man made X-Ray photons on demand. ... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ... Diagram of a zinc anode in a galvanic cell. ...

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 mid-section of the vacuum tube hollow, leaving room for the scan table and object or person to lie while the scan is performed. Cathode ray tube employing electromagnetic focus and deflection Cutaway rendering of a color CRT: 1. ... Diagram of a copper cathode in a Daniells cell. ... Diagram of a zinc anode in a galvanic cell. ...

Design disadvantage

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

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 x 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 x 360°/sec rotation speeds and lower radiation exposure. The latest version of the EBT eSpeed offers a 33ms sweep time. While there are very few of these scanners in use, this technology represents the fastest commercial CT temporal resolution.