![]() ![]() 77 The iridium hairpin technique is used with one gutter guide placed in the soft palate in the transverse plane and additional gutter guides placed vertically into the anterior tonsillar pillars, depending on the extent of the lesion. 76 The nylon tube technique also may be used to implant the soft palate. Iridium 192 hairpin or plastic tube techniques have been used by Mazeron and coworkers. Martinez, in Clinical Radiation Oncology (Third Edition), 2012 Implants of the Tonsillar Region, Including the Faucial Arch The core itself is approximately 3 to 4 mm long and 0.3 to 0.4 mm in radius. The active 192Ir core is usually made of an Ir-Pt alloy (10%-30% Ir and 70%-90% Pt) to make it more mechanically robust. The most probable energies are the 0.206 and 0.485 MeV, but they make up only a small percentage. The second, less probable, branch leading to 192Os* by EC also decays mainly via gamma emission to the ground state. This decay chain leads to 2.2 photons per β − decay. For the β − decay channels, de-excitation of 192Pt* to 192Pt (ground state) proceeds mainly via gamma emission and in a smaller fraction by internal conversion. This leads to a complex decay pattern resulting in 29 gamma emission peaks from 0.110 to 1.378 MeV, various characteristic x-rays, and numerous electrons up to 1.377 MeV. Hence, the production rate of 192Ir is limited by its own decay and by its transformation into 193Ir.ġ92Ir decays into platinum 192 ( 192Pt) via β − decay 95.1% of the time and the remaining 4.9% in osmium 192 ( 192Os) by EC. Interestingly, 192Ir has a high neutron capture cross section, allowing double-neutron capture by 191Ir into 193Ir. The material can be enriched so as to reduce the contamination of radioactive 194Ir from 193Ir and increase 192Ir production. 191Ir composes 37.3% of natural iridium, 193Ir making 62.7%. Jean Pouliot PhD, Luc Beaulieu PhD, in Leibel and Phillips Textbook of Radiation Oncology (Third Edition), 2010 Iridium 192ġ92Ir is produced in the nuclear reactor in the reaction 191Ir(n,γ) 192Ir. ![]()
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