This paper will discuss three 1D heat transfer problems associated with both conduction and radiation, which are mathematical models for a CNT used as a field electron emitter. CNT has attracted an increasing attention as a potentially excellent material for an electron emitter since around mid-90's. Predicting the current density and the temperature profile of CNT caused by the Joule heating associated with the current density is the key to understanding the physics of CNT as a field electron emitter. Thus, this is the focus of the paper.
KEYWORDS: X-rays, Sensors, X-ray sources, X-ray computed tomography, Medical diagnostics, Signal to noise ratio, Electron beams, Mammography, Signal detection, Angiography
The challenges that medical diagnostic x-ray source engineers must meet depend upon the modality. Cardiac-x-ray sources must improve both fluoro and cine high power output while maintaining small physical size and weight. Angiography must have small focal spots for higher magnification work as well as high power capability using the large focal spot. Some filtration is applied to modify the bremsstrahlung spectrum so that maximum contrast can be achieved with contrast-enhancing agents in the patient's body. Computed tomography (CT) sources have design requirements that take into account the source's increasingly rapid circular motion about the patient's body and tight specifications on focal spot motion and drift. The decrease in scan time requires an increase in source power in order to maintain sufficient x-ray photon flux density at the detector elements for proper signal-to-noise. Mammography x-ray sources face a demand for higher power in smaller focal spots at low electron accelerating voltage. Although focal spot sizes approach 0.1 mm, the resolution of small tissue abnormalities remains a current problem. Management of the dose to the patient is a concern that is common to all the modalities.
Proceedings Volume Editor (1)
This will count as one of your downloads.
You will have access to both the presentation and article (if available).
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.