Carbonization, ion beams

Figure 23 Variation of RBE as a function of depth in the carbon-ion beam used for clinical applications at HIMAC, Chiba, Japan (carbon-12, 290 MeV/u, SOBP 60 mm). The biological system is the well-codified intestinal crypt regeneration in mice. The selected criterion is 20 regenerating crypts per circumference after a single fraction irradiation. RBE determinations were performed at the beginning, middle, and end of the SOBP and at the level of the initial plateau. The dose-effect relationship for cobalt-60 is indicated for comparison. An estimation of the LET is presented for each depth where biological determinations were made. (From Gueulette, unpublished.)...

Figure 25 Treatment of a tumor of the base of skull with a carbon-ion beam. Comparison of the (physical) absorbed dose and of the biological dose (i.e., the dose weighted for the RBE variation in the carbon beam). The treatment is carefully planned in order to obtain a homogeneous biological dose to the PTV. For the same biological dose to the PTV, the normal tissues in the initial plateau receive a lower dose. (From Ref. 45.)...

Table 8 Results of Carbon-Ion Beam Therapy at NIRS (Treatments June 1994-August 2001)...

Furthermore the system is fully automated, self-tuning and needs little or no maintenance. The operator will consider the instmment as an analytic tool the fact that an accelerator is involved is incidental. Up to 50 solid graphite samples can be loaded in a carousel prior to analysis. COj samples can be admitted on line to the ion source. The ion source uses a primary caesium beam to sputter the sample under investigation to form a negative carbon ion beam. The ion beam is accelerated through the system to reach the detector with an energy of 2.5 MeV. A detailed description of the system can be found in Nucl. Instr. and Meth. B123 (1997) 159. 

Aeisenberg and Chabot and others used carbon-ion beams with... 

The strnctnral phase transformation from mnltiwalled CNTs to amorphous carbon nanowires is observed at the carbon-ion-beam irradiation (Snn et al. 2005). Single crystalline diamond nanorods with diameters of 4-8 nm and with lengths up to 200 nm have been successfully synthesized by hydrogen plasma posttreatment of mnltiwalled CNTs. A TEM is used to examine... 

Masunaga S, Ando K, Uzawa A et al (2008) Radiobiologic significance of response of intratumor quiescent cells in vivo to accelerated carbon ion beams compared with gamma-rays and reactor neutron beams. Int J Radiat Oncol Biol Phys 70 221-228... 

The basic advantages of charged particle beams such as, e.g., carbon ion beams as compared to conventional photon and electron beams are the inverted depth dose profile (Bragg peak characteristics) and the Increased biological effectiveness. 

A further advantage of carbon ion beams is the possibility to use positron emission tomography (PET) to verify the position of the treatment field in the patient quasi online during the treatment period [154]. This method is based on the small amount of radioactive, positron emitting and Isotopes produced by nude-... 

An electrochemical study of the protectiveness of carbon overcoats as thin as 5 nm has been reported [141], Polarization resistance of disk structures in 0.5 M sulfuric acid was measured. Disks coated with hydrogen-containing ion beam deposited carbon were found to have much lower corrosion rates than those coated with standard sputtered C of equivalent thickness. The composition of the sputtered carbons was varied by changing the sputtering gas. The corrosion rate depended on the type of carbon ion beam C-H < sputtered C-H, < sputtered C-N < sputtered C. The different corrosion rates may be a result of differences in both coverage and catalytic activity of the carbon layers. 

Matsumoto, H., Hayashi, S., Hatashita, M., Shioura, H., Ohtsubo, T., Kitai, R., Ohnishi, T., Yukawa, O., Fumsawa, Y, and Kano, E. (2000). Induction of radioresistance to accelerated carbon-ion beams in recipient cells by nitric oxide excreted from irradiated donor cells of human glioblastoma. Int. J. Radiat. Biol. 76, 1649-1657. 

Uses. The chemical inertness, thermal stability, low toxicity, and nonflammability of PFCs coupled with their unusual physical properties suggest many useflil applications. However, the high cost of raw materials and manufacture has limited commercial production to a few, small-volume products. Carbon tetrafluoride and hexafluoroethane are used for plasma, ion-beam, or sputter etching of semiconductor devices (17) (see loN implantation). Hexafluoroethane and octafluoropropane have some applications as dielectric gases, and perfluorocyclobutane is used in minor amounts as a dielectric fluid. Perfluoro-1,3-dimethyl cyclohexane is used as an inert, immersion coolant for electronic equipment, and perfluoro-2-methyldecatin is used for... 

As noted above, amorphous earbon films ean be produeed from earbon-eontaining gas phases (physieal vapour deposition, PVD). They ean also be produced from hydroearbon-eontaining gases (ehemical vapour deposition, CVD). Both PVD and CVD proeesses ean be thermally-aetivated or ean be plasma- and/or eleetrie field-assisted proeesses (e.g., mierowave assisted CVD and ion beam deposition). As a eonsequence a wide range of processes have been developed to form amorphous carbon films and a correspondingly complex nomenclature has evolved [70, 71]. 

Up to the present, a number of conventional film preparation methods like PVD, CVD, electro-chemical deposition, etc., have been reported to be used in synthesis of CNx films. Muhl et al. [57] reviewed the works performed worldwide, before the year 1998, on the methods and results of preparing carbon nitride hlms. They divided the preparation techniques into several sections including atmospheric-pressure chemical processes, ion-beam deposition, laser techniques, chemical vapor deposition, and reactive sputtering [57]. The methods used in succeeding research work basically did not... 

Aisenberg, S. and Chabot, R., Ion-beam Deposition of Thin Films of Diamond-like Carbon,"/. Appl. Phys.,Vo. 42,1971, pp. 2953-2958. 

Kimock, F. M. and Knapp, B. J., Commercial Applications of Ion Beam Deposited Diamond-like Carbon (DLC) Coatings," Surf. Coat. Technol, Vol. 56,1993,pp. 273-279. 

Toshiyuki, Hayashi, Akihito, Matsumuro, Mutsuo, Mura-matsu, Masao, Kohzaki, and Katsumi, Yamaguchi, "Wear Resistance of Carbon Nitride Thin Films Formed by Ion Beam Assisted Deposition," Thin Solid Films, Vol. 376, No. 1-2, 2000,pp. 152-158. 

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