The selective delivery of radionuclides to cancerous tissues remains a problematic issue. The lack of specificity and sensitivity for many therapeutic and diagnostic strategies limits their safety and efficacy by putting healthy organs and tissues at risk. This is especially true for lung tumors, which seem to have limited blood flow. Therefore, therapeutic and diagnostic strategies with high specificity are needed to overcome these limitations. Metastases are the main cause of patient deaths, accounting for approximately 90%. It is therefore imperative that a systemic targeting approach be developed that is specific to the tumor microenvironment rather than a single target. The specific aims of this dissertation were to: 1) develop radiolabeled gold nanoparticles (AuNPs) for tumor therapy and imaging, 2) develop a nose-only mouse nebulizer system for use with/within optical or radioisotope imaging equipment, and 3) test the theranostic nanoparticles and nebulizer system on a mouse lung tumor bearing model. The first aim was performed by synthesizing I-125, Au-198, and As-211 AuNPs. The second aim utilized Solidworks 3D CAD software and employed 3D printing technology for fabrication. The third aim was performed with fluorescent Cy5.5 labeled nanoparticles designed to be used for diagnostic imaging.