Читать книгу Leksell Radiosurgery - Группа авторов - Страница 85

The principals of radiation protection and licensing of Gamma Knife units are covered by the Code of Federal Regulations (10 CFR parts 20, 35) [1] outlined by the Nuclear Regulatory Committee. Among others, these regulations set dose limits to radiation workers and the public, and also to pregnant radiation workers. The tungsten and steel housing of a Gamma Knife unit (Fig. 1) act as a primary barrier to reduce the exposure to personnel. Tungsten is a metal alloy that absorbs radiation from the sources, with the initial activity of about 6,600 Ci or for 192 sources about 34 Ci per source. A Curie (Ci) is a unit of radioactivity, corresponding to 3.7 × 10¹⁰ disintegrations per second. Additionally, a concrete vault houses the Gamma Knife unit with wall thicknesses of approximately 10–14 inches. This reduces the exposure from leakage and scattered radiation from the patient to below regulatory limits.

Fig. 1. Cross-sectional layout of a Perfexion or ICON, shown without CBCT. Courtesy of Elekta.