Carbon Nanotube Electron Emitter for X-ray Imaging

Ryu, Jae-Chun; Kang, Jung Su; Park, Kyu Chang

doi:10.3390/ma5112353

Cited by 31 publications

(20 citation statements)

References 12 publications

(15 reference statements)

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“…In addition, they demonstrated peak pulse currents of up to 28 mA (emitted area not stipulated), without vacuum breakdown, at an anode potential of 14 kV. Using CVD grown CNT arrays, Ryu et al [205] reported emission currents of up to 90 mA (emitted area not stipulated) in a diode configuration, although in a gate-controlled triode arrangement, the beam currents were substantially reduced.…”

Section: High Beam Currentmentioning

confidence: 95%

“…A resist-assisted patterning process was used to produce a cathode assembly consisting of a gate and focusing electrode. This assembly was approximately 0.5 mm × 2.0 mm and gave an isotropic focal spot [205]. Ryu et al also described a further shaping technique for post processing the as-grown vertically aligned CNTs.…”

Section: Beam Profilingmentioning

confidence: 98%

“…For a high performing emitter this aging, also termed seasoning, is not desirable and CNTs of very uniform height and diameter are preferred, as evidenced by Teo et al [166], to obviate the need for such post-growth treatments. Nevertheless, part of the Ryu et al ageing process [205] was to remove the Ni catalyst particles at the CNTs apex, which they argued reduced the emission current. Detailed analysis and theoretical studies surmising the emission implications of the metallic nanoparticle in the emitter tip are lacking in the literature.…”

Section: Beam Profilingmentioning

confidence: 99%

“…Using Si-supported CNT arrays, Ryu et al demonstrated the potential of CVD in X-ray source applications [205]. A resist-assisted patterning process was used to produce a cathode assembly consisting of a gate and focusing electrode.…”

Section: Beam Profilingmentioning

confidence: 99%

“…Many groups have grown CNTs, by CVD or derivatives thereof, directly on conical or other shaped tips, on common Spindt-like materials [213], Si [169,205,214] or bulk metals [200]. As such, these systems do not exploit the full geometric potential of the CNTs; they simply amplify, often only marginally, the existing field enhancement factor of the tip structures and almost always result in an induced asymmetry in the electron beam profile that is challenging to accommodate with conventional electrostatic focussing.…”

Section: Beam Profilingmentioning

confidence: 99%

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X-ray generation using carbon nanotubes

et al. 2015

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Since the discovery of X-rays over a century ago the techniques applied to the engineering of X-ray sources have remained relatively unchanged. From the inception of thermionic electron sources, which, due to simplicity of fabrication, remain central to almost all X-ray applications, there have been few fundamental technological advances. However, with the emergence of ever more demanding medical and inspection techniques, including computed tomography and tomosynthesis, security inspection, high throughput manufacturing and radiotherapy, has resulted in a considerable level of interest in the development of new fabrication methods. The use of conventional thermionic sources is limited by their slow temporal response and large physical size. In response, field electron emission has emerged as a promising alternative means of deriving a highly controllable electron beam of a well-defined distribution. When coupled to the burgeoning field of nanomaterials, and in particular, carbon nanotubes, such systems present a unique technological opportunity. This review provides a summary of the current state-of-the-art in carbon nanotube-based field emission X-ray sources. We detail the various fabrication techniques and functional advantages associated with their use, including the ability to produce ever smaller electron beam assembles, shaped cathodes, enhanced temporal stability and emergent fast-switching pulsed sources. We conclude with an overview of some of the commercial progress made towards the realisation of an innovative and disruptive technology.

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Section: High Beam Currentmentioning

confidence: 95%

Section: Beam Profilingmentioning

confidence: 98%

Section: Beam Profilingmentioning

confidence: 99%

Section: Beam Profilingmentioning

confidence: 99%

Section: Beam Profilingmentioning

confidence: 99%

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X-ray generation using carbon nanotubes

et al. 2015

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A Detailed Study on Carbon Nanotubes: Properties, Synthesis, and Characterization

Tripathi

Sharma

Pavelyev

et al. 2022

Chemically Modified Carbon Nanotubes for Commercial Applications

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An update on carbon nanotube‐enabled X‐ray sources for biomedical imaging

Puett

Inscoe

Hartman

et al. 2017

WIREs Nanomed Nanobiotechnol

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A new imaging technology has emerged that uses carbon nanotubes (CNT) as the electron emitter (cathode) for the X-ray tube. Since the performance of the CNT cathode is controlled by simple voltage manipulation, CNT-enabled X-ray sources are ideal for the repetitive imaging steps needed to capture threedimensional information. As such, they have allowed the development of a gated micro-computed tomography (CT) scanner for small animal research as well as stationary tomosynthesis, an experimental technology for large field-of-view human imaging. The small animal CT can acquire images at specific points in the respiratory and cardiac cycles. Longitudinal imaging therefore becomes possible and has been applied to many research questions, ranging from tumor response to the noninvasive assessment of cardiac output. Digital tomosynthesis (DT) is a low-dose and low-cost human imaging tool that captures some depth information. Known as three-dimensional mammography, DT is now used clinically for breast imaging. However, the resolution of currently-approved DT is limited by the need to swing the X-ray source through space to collect a series of projection views. An array of fixed and distributed CNT-enabled sources provides the solution and has been used to construct stationary DT devices for breast, lung, and dental imaging. To date, over 100 patients have been imaged on Institutional Review Board-approved study protocols. Early experience is promising, showing an excellent conspicuity of soft-tissue features, while also highlighting technical and post-acquisition processing limitations that are guiding continued research and development. Additionally, CNT-enabled sources are being tested in miniature X-ray tubes that are capable of generating adequate photon energies and tube currents for clinical imaging. Although there are many potential applications for these small field-of-view devices, initial experience has been with an X-ray source that can be inserted into the mouth for dental imaging. Conceived less than 20 years ago, CNT-enabled X-ray sources are now being manufactured on a commercial scale and are powering both research tools and experimental human imaging devices.

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Carbon Nanotube Electron Emitter for X-ray Imaging

Cited by 31 publications

References 12 publications

X-ray generation using carbon nanotubes

X-ray generation using carbon nanotubes

A Detailed Study on Carbon Nanotubes: Properties, Synthesis, and Characterization

An update on carbon nanotube‐enabled X‐ray sources for biomedical imaging

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