A multi-beam compact tomosynthesis system has been developed to acquire chest X-ray images and provide reconstructed 3D X-ray images. The system uses 43 field emission X-ray sources based on carbon nanotubes (CNTs). The CNT-based X-ray source consists of an anode array, gate array, and electron gun (e-gun) array and is stationary while the digital X-ray detector moves. To analyze 3D data of the electron emission trajectory in the multi-beam X-ray source, simulation software which is CST Particle Tracking Studio was used. In this developed system, we applied a vacuum external projection type X-ray source device. Specifically, it relates to a vacuum externally protruding type X-ray source device that can be easily replaced by protruding the lower part of the unit X-ray source to the outside of the vacuum.
In this study, we have developed the digital tomosynthesis system which is an improvement over conventional tomosynthesis systems as it is lighter, is easier to load the CNT e-gun, eliminates motion blur since the gantry is fixed, and provides fast and high-resolution images because of the reduction of the focal spot size with the use of multiple CNT-based X-ray sources.
A stationary digital tomosynthesis system using 43 carbon nanotube (CNT) field emission X-ray sources has been developed to overcome some issues in traditional chest tomography synthesis systems using a single X-ray source. This new system utilizes CNTs to digitize X-ray source, allowing for the acquisition of high-resolution 3D X-ray images without motion blur. The system has been compared to a traditional tomosynthesis system using a thermionic source based on filament. This study reports a multi-array X-ray device, in which a body part made of an insulating material, which is a non-metallic material, provides a natural insulating environment to generate high-performance X-ray devices.
In this study, the new CNT field emitter-based X-ray sources are designed, fabricated, and developed to improve resolution compared to the filament-based X-ray sources. Also, we compare the geometric difference between two tomosynthesis systems, and it is expected to provide high-resolution 3D images for chest diagnosis in the medical field.
We designed and developed a carbon nanotube (CNT)-based reflective digital cell irradiation system capable of irradiating cells. The chemical and physical properties of the CNT synthesized directly on the patterned substrate were confirmed, and the field emission characteristics with a maximum anode current of 10 mA were evaluated through the I-V curve. Also, electrostatic simulation was conducted to confirm the electric field distribution and the electron beam trajectory. According to the duty (27.3 mGy at anode on time 10 sec, duty 50 %), the anode voltage (25.2 mGy at anode on time 10 sec, duty 50 %, anode voltage 40 kV) and the distance between the window and the cell stage (anode on time 10 sec, duty 50%, anode voltage 40 kV, 19.4 mGy), the function of the system was verified by obtaining the dose emitted from the system. This study confirmed that it is suitable as the cell irradiation system for studying the radiobiological effects of low-dose radiation-irradiated cells.
In this paper, we demonstrated the comparison of digital-based CNT and analogue-based filament X-ray sources by taking the X-ray images of ACR mammo phantom for developing the intraoperative specimen X-ray system. The X-ray image of ACR mammo phantom taken at 25 kV 1 mA by filament shows overall the better image quality. However, when X-ray images of phantom were compared at 40 kV 1 mA by both sources, it showed that CNT X-ray source showed better image quality because of Aluminum window.
When designing an X-ray monoblock for portable systems, the size and compactness of X-ray tube plays an important role. The monoblocks normally contains high voltage unit and X-ray tube immersed together inside the sea of insulating oil and sealed by Aluminum or plastic frame. Normally, mononblocks built for 100 kV or higher X-ray tube are quite bulky, not because of the high voltage source unit but because of the huge size of glass enveloped X-ray tube. The compactness of X-ray tube can decrease the size of mononblock and it can subsequently increase the portability of X-ray system. There are efforts done to decrease the size of X-ray tube by replacing the glass envelope with metal ceramic frames in CT X-ray tubes which are categorized as Rotating X-ray tubes. However, there are few or almost no researches on looking for an alternative to avoid making bulky glass X-ray tubes for Stationary tubes. It might be partially because the discovery of Xray tubes is all connected to the glass vacuum tubes. Other reasons could be due to matureness of glass making technology, which though still lacks automation but is cheaper and easier. Our group has realized that using ceramic to maintain vacuum and use it as an alternative to glass envelop can increase the robustness and compactness of filament X-ray tubes. Moreover, it can also help engineers to develop smaller and lighter monoblock for high-end X-ray systems. Thus, in this study, we report a development of compact 120 kV ceramic-based filament type X-ray tube for panoramic dental imaging. We have compared in-house built ceramic X-ray tube with commercial glass X-ray tube which is most commonly used for 100 kV panoramic dental X-ray imaging system. The result shows that despite the 38 % reduction in size, ceramic tube has better IV characteristic with similar filament size and higher limiting spatial resolution compared to glass X-ray tube. Moreover, we have successfully performed all the X-ray experiments using 100 kV 500W custom built high voltage source which can be used for making monoblocks.
A fully commercialized intraoperative specimen radiographic system (IOSRS) based on carbon nanotube (CNT) emitter has been developed and the optimization of electron beam (E-beam) focusing characteristic of X-ray source is analyzed in this paper. The IOSRS can be used inside the operation theatre and helps reduce the surgery time during breast conserving surgery by confirming the extent of margin on specimen. For this, a highly focused X-ray source is required which depends on the focusing structure of Electron gun (E-gun). Normally, a separate focuser and grid are added in the filament X-ray tube to produce a narrow E-beam and perfectly digitalized X-ray pulses, respectively. However, in CNT based X-ray tubes, the focuser and grid can be integrated as one structure called self-focusing gate structure. The self-focusing gate structure can extract electrons and focus the E-beam producing perfect pulses of X-ray dose and simultaneously enhancing the spatial resolution quality of X-ray source. In this study, we have investigated the effect of changing the length of selffocusing gate structure on the spatial resolution capability of X-ray system and its effect on the field electron emission performance of CNT E-gun.
KEYWORDS: Radiation effects, Beryllium, 3D modeling, Scanning electron microscopy, Radiation oncology, Radiotherapy, Particles, Metals, Medicine, Medical research
Radiation research primarily aims to improve radiation therapy and the use of radiation on soft materials. There are many reports available on the effects of high-dose radiation on cells, but the effects of low-dose radiation still require much scientific evidence. Therefore, we intend to study the effects of low-dose irradiation on cell internal structures by cold cathode field emission carbon nanotube (CNT)-based cell irradiator. Hence, we designed a CNT-based microbeam system to irradiate cells. CNT emitter was fabricated by synthesizing CNTs on point shaped substrate. The growth of CNTs was confirmed by scanning electron microscope (SEM). The aging process was carried out to improve the performance of the CNT emitter and the I-V characteristic was measured. We also conducted the simulation study in order to confirm the electric field change and the electron beam trajectory.
A Carbon nanotube (CNT) cold cathode emitter-based compact X-ray tube for X-ray application is studied in this paper. In the electron gun, the conventional filament was replaced by CNT emitter; CNTs were grown on metal alloy substrate. Using this electron gun, electron emission can be controlled by applying voltage rather than heating. Up to 2 mA tube current can be generated by this CNT electron gun. Also, the pulsed tube current and pulsed radiation dose can be generated by using MOSFET circuit. We measured the radiation dose generated in 30 frames per second, and confirmed that the waveform was generated as a square wave. From that waveform, it was confirmed that unnecessary radiation exposure can be minimized. The body of the X-ray tube is made of ceramic, which has strong durability against impact and high temperature. The ceramic used for the tube has an insulation distance of 30 mm and shows stable insulation performance in an environment where a voltage of 70 kV is applied. Using this X-ray tube, we successfully obtained X-ray images of various objects with acceleration voltages between 45 kV and 70 kV.
We designed and developed the vacuum sealed x-ray tube based on carbon nanotube(CNT) field emitter for mobile medical x-ray devices and also design the test bed for CNT x-ray tube. The CNT was synthesized by chemical vapor deposition(CVD) method on a metal alloy substrate. The grown CNT is assembled with a gate and a focuser and then combined into an electron gun(e-gun) through a brazing process. The the e-gun had an aging process inside the vacuum chamber. As a result of aging, the CNT e-gun was able to generate anode current of 1.5 mA at electric field of about 4 V/μm, and field emission current was also stabilized. After the aging process, the e-gun was brazed into a ceramic X-ray tube inside a high-temperature furnace at a vacuum degree of E-06 torr and vacuum sealed. Field emission characteristic was measured using this X-ray tube and compared with an e-gun, and almost similar results were obtained. Incase of Xray tube, we applied a higher electric field while controlling the current at 500ms intervals through pulse driving. As a result, X-ray images of human teeth were successfully acquired using CNT X-ray tubes.
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.
We developed a compact vacuum X-ray tube using an alumina body instead of glass. A filament is implanted as a cathode which follows Richardson-Dushman equation. After aging the filament to eliminate impurities on the filament which improves performance of filament before tubing, tube current was obtained from anode voltage of 6kV, 3mA to 40kV, 3.15mA. The pulse high voltage generator is designed and developed to make the tube less stressful. With the ceramic X-ray tube, X-ray images of human breast and teeth phantom were successfully obtained, verifying the potential of the compact alumina vacuum sealed X-ray tube in X-ray application for medical imaging.
Based on the breast imaging and reporting data system (BI-RADS) for mammography (MMG) and types of cancer cells detected, a patient is listed into various categories which determine whether they should undergo biopsy or not. Generally, patients under the BI-RADS category 4 or 5 have to go through surgery. During the surgery, a pathological examination is performed with the help of a microscope and additional X-ray images of the removed tissue or breast specimen are taken to determine the positive and negative surgical margins. Although the pathological examination is the best way to determine carcinoma at the inked margin, it consumes a significant amount of time and makes the duration of the surgery longer. In this study, we propose the open-type carbon nanotube (CNT)-based X-ray system, which can be helpful to determine the carcinoma on breast specimen during breast surgery. The technique proposed in this study successfully obtained X-ray images of a breast specimen with visibly clear cancer masses. These results could pave the way for efficient determination of surgical margins by eliminating the time-consuming histological procedures.
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