Gold

¹⁹⁸Au has several medical uses. It has been used as both a diagnostic tool and a treatment option for cancer [530], [531]. –As a diagnostic tool, colloidal ¹⁹⁸Au is injected into the affected organ. Normal cells will take up the gold colloid, but tumor cells will not. Therefore, an abscess will show up as a “cold area” on a scan [531]. –As a treatment option, gold is intended to provide localized irradiation and can be implanted or injected into the affected area. When implanted, the gold “seed” offers an advantage over other materials in that it can be left in place due to its short half-life (2.7 days). As a colloidal injection, ¹⁹⁸Au has been found to produce improvement from a wide variety of cancers [530]. Figure 4.79.1a and 4.79.1b, respectively, show squamous cell carcinoma (cancer) on the lower left eyelid of a cat and the eyelid 6 weeks after implantation of ¹⁹⁸Au seeds [532]. Recent studies have shown the effectiveness of ¹⁹⁸Au nanoparticles and nanodevices in reducing tumor size in mice while minimizing radiation spread to other areas [530], [533], [534]. ¹⁹⁸Au has been studied and successfully used as an anti-inflammatory (a substance or treatment that reduces the body tissues response to harmful stimuli, such as swelling) for improving arthritic conditions [535], [536].