"Even though IR is a well-known genotoxic agent and human carcinogen, it is also widely used to effectively diagnose and treat cancer (Little, 1999, 2000; Pollack et al., 2000; Roof et al., 2003; De Potter et al., 2006; Erven and Van Limbergen, 2007). Since 1902 when the first radiation-induced cancer was reported (Little, 2000, 2003), and almost 100 years after radiation was used for the first time to treat tumors (Gramegna, 1909), it still remains the number one diagnostic and treatment tool for the majority of cancers (Pollack et al., 2000; Roof et al., 2003; De Potter et al., 2006; Erven and Van Limbergen, 2007). While modern cancer radiation therapy has led to increased patient survival rates, the risk of treatment-related deleterious effects, including secondary cancers, is becoming a growing clinical problem (Leone et al., 1999). Relatively recent findings suggest that even fairly low doses of IR, such as those used in diagnostic procedures (e.g., X-ray or computer tomography), can lead to the development of radiation-induced cancers (Preston-Martin et al., 1989; Doody et al., 2000; Liu et al., 2002; Brenner and Hall, 2004). This risk of developing secondary treatment-related cancers is even more pronounced in children and young adults who received either diagnostic or therapeutic exposure to IR (Hildreth et al., 1989; Infante-Rivard et al., 2000; Hall, 2002; Shu et al., 2002; Kleinerman, 2006)."