Antecedentes de la sentencia

In conclusion we have constructed a novel CNT field emission based electron cellular irradiator. The system comprises a wide variety of components, and in particular has

required the development of a CNT cathode. A first phase single microbeam has been developed, characterized, and used for a variety of cell irradiation procedures. The single beam system is capable of irradiating over very small areas (23 um diameter) and even single cells given adequate cell spacing. Better collimation techniques could produce slight

enhancement of the current capability. Nevertheless given the scattering of electrons even out of small apertures there seem to be some fundamental limitations to the minimum beam size capability of electron irradiators operating in the 25-30 kV range. Despite these

limitations the single pixel electron irradiator has demonstrated a high dynamic dose rate range, allowing for fast irradiation over several orders of dose magnitude. Additionally the system could be easily reproduced and installed for use more broadly than other types of irradiators.

For cell irradiation in general there is still much work to be done, both in biological experimentation and in determining what experiments to carry out. The presence of an irradiation bystander effect remains to be evaluated as evidence is present in some cases and not in others. It is not known whether the bystander response is merely an occasional

response to irradiation by some types of cells or whether it is merely an elusive effect. The UNC cell irradiator provides a demonstration of increased access to cell irradiation which could help elucidate some of the unknown inner workings of cells.

In addition to the achievements with the single pixel system and the potential contribution to research in radiobiology, the work done on the multi-pixel system has demonstrated the basis for a functioning multi beam system, a first in the microbeam research community. Although the current multi-beam system does not surpass the

capabilities of many of the more advanced cell irradiators, particularly the ion beam systems, the introduction of a multi-beam system and the research completed have laid the

groundwork for new types of experiments exploiting the multi-beam platform. This system introduces the capability of multiple parallel irradiations with dose and dose rate variability. Also future improvements could include the expansion of the system to an even larger number of beams, e.g. 10x10 or even 100x100. The engineering of the system still requires some improvement, but many of the basic challenges and requirements have been identified that will need to be overcome for a future system.

Finally over the course of the research and development of our microbeam systems other opportunities and avenues have been investigated as related to cell irradiation and fabrication of key components. While the single cell and even sub-cellular irradiation capabilities will remain in demand, the use of alternative radiation geometries, such as large apertures and slit irradiation, may also prove to be of interest. In addition new fabrication and engineering techniques, such as the DRIE-based components, can serve to advance the performance of various types of cellular irradiators. There is still a great amount of

therapy advances that will enhance the effectiveness of cancer treatment. The CNT field emission based electron cellular irradiator represents one step in that direction.

References

1. D. Modroukas, V. Modi, and L.G. Frechette, Micromachined silicon structures for free-convection PEM fuel cells. Journal of Micromechanics and Microengineering, 2005. 15: p. S193-S201.

2. E. Brauer-Krisch, et al., New irradiation geometry for microbeam radiation therapy. Physics in Medicine and Biology, 2005. 50: p. 3103-3111.

Publication List

1. D. Bordelon, J. Zhang, S. Graboski, A. Cox , E. Schreiber , O. Zhou , S. Chang. “A Nanotube Based Electron Microbeam Cellular Irradiator for Radiobiology Research.” Rev. Sci. Instrum. 79, 125102 (2008).

2. Z. Liu, G. Yang, Y.Z. Lee, D. Bordelon, J.P. Lu, and O. Zhou. "Carbon Nanotube Based Micro-Focus Field Emission X-ray Source for Micro-Computed Tomography." Applied Physics Letters 89, 103111 (Sept 2006).

3. S. Chang, J. Zhang, D. Bordelon, E. Schreiber, A. Cox, and O. Zhou. “Development of a nanotechnology based low LET multi-microbeam array single cell irradiation system.” Radiation Protection Dosimetry, 122(1-4), 323-326, 2006.

Abstracts

1. J. Zhang, D. Bordelon, J. Snider, E. Schreiber, A. Cox, O. Zhou, and S. Chang. “Feasibility Study of Microbeam Radiation Therapy Using a Carbon Nanotube Field Emission Based Electron Microbeam Irradiator.” Medical Physics, 36(6): 2775-2775, 2009.

2. D. Bordelon, J. Zhang, S. Graboski, A. Cox, E. Schreiber, O. Zhou, and S. Chang. “Development of a carbon-nanotube field emission based multi-pixel microbeam cellular irradiation system.” Medical Physics, 35(6): 2899, 2008

3. S. Chang, J. Zhang, D. Bordelon, S. Graboski, E. Schreiber, A. Cox, and O. Zhou. "Feasibility Study of a Carbon Nanotube Field Emission Microbeam System for Cellular Irradiation." Med. Phys. 34, 2455 (June 2007)

4. S. Chang, J. Zhang, D. Bordelon, E. Schreiber, A. Cox, O. Zhou. "Development of a carbon nanotube based low -LET multi-pixel microbeam array." Rad. Res 166, 658- 659 (2006).

5. S. Chang, J. Zhang, D. Bordelon, E. Schrieber, A. Cox, O. Zhou. "A carbon nanotube based low LET multi-microbeam array singel cell irradiation system." Medical

Physics (6): 2271, (June 2006) Selected conference presentations

1. D. Bordelon, J. Zhang, S..Graboski, A. Cox, E. Schreiber, O. Zhou, and S. Chang. “Development of a carbon-nanotube field emission based multi-pixel microbeam cellular irradiation system”; The American Association of Physicists in Medicine (AAPM) 50th

2. D. Bordelon, J. Zhang, S. Graboski, E. Schreiber, A. Cox, O. Zhou, and S. Chang. “Development of carbon nanotube field emission multi-pixel electron beam cellular irradiation system”; The 8th

International Workshop on Microbeam Probes of Cellular Radiation Response, Chiba, Japan, November 2008 (oral presentation)

3. S. Chang, J. Zhang, D. Bordelon, S. Graboski, E. Schreiber, A. Cox, and O. Zhou. “Feasibility study of a carbon nanotube field emission microbeam system for cellular irradiation”; The American Association of Physicists in Medicine (AAPM) 49th Annual Meeting, Minneapolis, Minnesota, July 2007. (poster)

4. J. Zhang, D. Bordelon, S. Graboski, E. Schreiber, A. Cox, O. Zhou, and S. Chang. “Development of a nanotechnology based low LET multi-microbeam array single cell irradiation system”; CCNE 2007 Cancer Nanotechnology Symposium, Chapel Hill, NC, November 2007. (poster)

5. J. Zhang, D. Bordelon, S. Graboski, E. Schreiber, A. Cox, O. Zhou, and S. Chang. “Development of a nanotechnology based low LET multi-microbeam array single cell irradiation system”; Materials Research Society (MRS), North Carolina Symposium, November 2006. (poster)

6. J. Zhang, D. Bordelon, S. Graboski, E. Schreiber, A. Cox, O. Zhou, and S. Chang. “Development of a nanotechnology based low LET multi-microbeam array single cell irradiation system”; CCNE 2006 Cancer Nanotechnology Symposium, Chapel Hill, NC, November 2006. (poster)

7. S. Chang, J. Zhang, D. Bordelon, E. Schreiber, A. Cox, and O. Zhou. “Development of a carbon nanotube based low LET multi-pixel microbeam array”; 7th

International Workshop on Microbeam Probes of Cellular Radiation Response, New York City, New York, March 2006. (oral presentation)

8. S. Chang, J. Zhang, D. Bordelon, E. Schreiber, A. Cox, and O. Zhou. “Development of a nanotechnology based low LET multi-microbeam array single cell irradiation system”; 14th

International Symposium on Microdosimetry, Venice, Italy, November 2005. (oral presentation)