We present an electron emitter for multi-X-ray source system such as computed tomography (CT) or tomosynthesis. The electron emitter used in the X-ray source was fabricated using carbon nanotubes with excellent electrical properties as a cold cathode. A metal-oxide-semiconductor field-effect transistor (MOSFET) circuit was added between the cathode of the electron emitter and the ground to enable pulse driving according to the input signal. The field emission characteristics of the electron emitter were tested in a self-made vacuum system. Pulse driving of the electron emitter was performed at a frequency of 10 kHz and a duty of 50%, and a maximum cathode current of 3.9 mA flowed at a gate voltage of 2.1 kV. In addition, it was possible to take X-ray images of the chest phantom and metronome using an X-ray source made with a CNT-based electron emitter.
We designed an X-ray source using a carbon nanotubes-based electron emitter. Carbon nanotubes (CNTs) having a cylindrical structure have excellent electrical and mechanical properties. For this reason, it is suitable as an electron emitter device of a field emission method and can be used as the X-ray source. CNTs were synthesized on an alloy substrate through chemical vapor deposition (CVD) method, and the substrate was used as a cathode in an electron emitter. The CNT-based emitter consists of a gate and a CNT cathode, and the emitter together with an anode constitutes an X-ray source. To improve the emitter's electron emission characteristics and durability, a MOSFET circuit was added between the CNT cathode and ground to enable pulse driving. In addition, the possibility of using the miniaturized X-ray sources as a multi-X-ray source arrays were confirmed by using the deMUX circuit to switch multiple emitters. The field emission characteristics of the CNT-based X-ray sources were analyzed, and it was confirmed that an X-ray image could be obtained.
A microfocus X-ray source based on carbon nanotube (CNT) emitter grown by chemical vapor deposition is presented in this paper. The microfocus X-ray source is developed for the intraoperative specimen radiographic system, which can be used inside the operation theatre and helps reducing the surgery time during breast conserving surgery by confirming the extent of margin on specimen. This high focusing X-ray source is realized by growing CNTs on pointed structures. The field emission characteristic shows that maximum anode current of 1mA, which corresponds to a maximum emission current density of 500 mA/cm2 from the CNT-based point emitter. The optimized parameter for the assembly of electron gun was achieved by using commercially available CST simulation software. Consequently, this microfocus X-ray tube could produce X-ray image of multilayer printed circuit board showing fine lines of integrated circuit.
In order to diagnose diseases in complex areas such as the chest, an X-ray system of a suitable type is required. Chest tomosynthesis, which acquires a reconstructed 3D image by taking X-ray images from various angles, is one of the best image acquisition technologies in use. However, one major disadvantage of tomosynthesis systems with a single X-ray source is the motion blur which occurs when the source moves or rotates to change the acquisition angle. To overcome this, we report a stationary digital tomosynthesis system, which uses 85 field-emission type X-ray sources based on carbon nanotubes (CNTs). By using CNT-based electronic emitters, it is possible to miniaturize and digitize the X-ray system. This system is designed such that a maximum of 120 kV can be applied to the anode to obtain chest X-ray images. The field emission characteristics of the CNT-based emitters are measured, and X-ray images were obtained using the stationary multi X-ray source system, confirming its applicability to chest Tomosynthesis.
KEYWORDS: X-ray sources, X-rays, X-ray imaging, Chest, 3D image reconstruction, Carbon nanotubes, Sensors, Medical research, 3D image processing, Digital imaging
Digital chest tomosynthesis that provides a reconstructed 3D chest image is a superior technique to detect chest diseases. As it is difficult to detect diseases like lung cancer with conventional 2D digital chest X-ray technology (CXT), digital chest tomosynthesis improves upon the many of the limitations inherent in the 2D digital CXT. In this study, we report a digital chest tomosynthesis system (D-CTS) that can generate multi X-ray information for the reconstruction of a 3D Xray chest image. The D-CTS reported herein employs an array of carbon nanotube (CNT) emitter-based cold cathode electron-guns that are triggered in sequence to provide a gantry-less system (Figure 1). The CNTs are achieved by direct growth on a metal substrate and have a spaghetti-like structure (Figure 2) with fast response to electrical bias under vacuum conditions. Unlike conventional rotating type systems with gantries, our CTS has the advantage of less motion blur in image acquisition, given its stationary position. Additionally, the switching from one electron-gun (e-gun) to the next is much faster than the speed of conventional gantries, allowing faster acquisition time t required for digital operation. This system shows outstanding field emission property for taking X-ray images. The design, fabrication process and imaging processing of the multi-beam CNT X-ray system will be discussed during the presentation.
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