This study aims to propose a novel method for multi-beam tomosynthesis using a single-beam x-ray source based on carbon nanotubes (CNTs) and compact vacuum CNT-based x-ray tubes are arranged on a 3D hemispherical curve. The proposed method enables each member of a multi-beam x-ray gantry to face the center of the same field of view (FOV), which has potential applications in medical imaging. This study evaluates the feasibility of our proposed method and its potential advantages over existing methods.
We have designed a 160kV radiation source based on carbon nanotubes (CNT) capable of irradiating cells. The functionality of the designed system was verified by assessing the physical and chemical properties of directly synthesized CNT and the resulting x-ray dosage emitted. The conventional x-ray source widely used until now employs an analog method that generates thermal electrons through filament heating. To overcome the limitations of this existing analog method, a novel digital x-ray tube capable of instantaneously controlling power became essential. Taking these aspects into consideration, our study developed a 160kV x-ray source based on CNT, enabling digital control of x-ray energy and dosage. We anticipate that our developed source can find applications in the field of cell therapy in the future.
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.
This paper investigates a bipolar high voltage driven carbon nanotube-based X-ray tube. For field electron emission, an electric field must be formed between the gate and the cathode, and a strong negative voltage must be applied to the cathode. A circuit capable of field emission and cathode negative voltage application is designed with a negative power supply using only one negative high voltage source and a resistor for this purpose. The CNTs grown on the metal substrate can generate a stable tube current of 3 mA, and X-ray images were obtained using this tube. Both bipolar driving and unipolar driving are tested under the same conditions to determine the difference between the two driving methods. This result confirms that there is no difference in image quality when only the anode is subjected to 60 kV and when the anode and cathode are subjected to +30 kV and -30 kV, respectively. As a result, it has been confirmed that bipolar driving is less prone to arcing and that image quality can be maintained because the burden on the anode is lower than in unipolar driving.
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.
In fluoroscopy, X-rays are used to obtain the real-time moving images of the human anatomy. To do so, a pulsed fluoroscopy is used so that patient and staffs are exposed to minimum radiation possible. However, in most medium priced pulsed fluoroscopy systems, X-ray tube without grid is used. The grid-less X-ray tube cannot produce perfect digital pulses due to inherent problem associated with thermionic emission of filament. Thus, the patient is exposed to unnecessary radiation using conventional Fluoroscopic system. This problem can be easily solved using carbon nanotube (CNT) based digital X-ray tubes and are much cheaper to manufacture than grid controlled filament based X-ray tubes. In this study, we have developed 120 kV CNT-based digital X-ray tubes for pulsed fluoroscopy that can be operated at very high frequency (~ MHz) producing low radiation dose during X-ray imaging. The DC and pulsed performance of Xray tube is studied, and the X-ray imaging of human skull is done with relatively low X-ray dose by pulsing the X-ray tube at 25 kHz. The commercial high voltage sources, function generator and N type-MOSFET were used for high-speed switching of E-beam during X-ray emission. This paper could help the radiologists and all the medical personnel understand the advantages of CNT based X-ray technology over filament for X-ray imaging use low dose radiation.
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.
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